diff --git a/CHANGELOG.md b/CHANGELOG.md
index fc45839147..96a569d315 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,7 @@ should change the heading of the (upcoming) version to include a major version b
 
 - Updated `Experimental_DefaultFormStateBehavior` to add a new `constAsDefaults` option
 - Updated `getDefaultFormState()` to use the new `constAsDefaults` option to control how const is used for defaulting, fixing [#4344](https://github.com/rjsf-team/react-jsonschema-form/issues/4344), [#4361](https://github.com/rjsf-team/react-jsonschema-form/issues/4361) and [#4377](https://github.com/rjsf-team/react-jsonschema-form/issues/4377)
+- Use `experimental_customMergeAllOf` option in functions that have previously missed it.
 
 ## Dev / docs / playground
 
diff --git a/packages/docs/docs/api-reference/utility-functions.md b/packages/docs/docs/api-reference/utility-functions.md
index a6b0455234..1bc00e0cfb 100644
--- a/packages/docs/docs/api-reference/utility-functions.md
+++ b/packages/docs/docs/api-reference/utility-functions.md
@@ -899,7 +899,7 @@ Returns the superset of `formData` that includes the given set updated to includ
 - [rootSchema]: S | undefined - The root schema, used to primarily to look up `$ref`s
 - [includeUndefinedValues=false]: boolean | "excludeObjectChildren" - Optional flag, if true, cause undefined values to be added as defaults. If "excludeObjectChildren", cause undefined values for this object and pass `includeUndefinedValues` as false when computing defaults for any nested object properties.
 - [experimental_defaultFormStateBehavior]: Experimental_DefaultFormStateBehavior - See `Form` documentation for the [experimental_defaultFormStateBehavior](./form-props.md#experimental_defaultFormStateBehavior) prop
-- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf<S> - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_customMergeAllOf) prop
+- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf<S> - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_custommergeallof) prop
 
 #### Returns
 
@@ -916,6 +916,7 @@ Determines whether the combination of `schema` and `uiSchema` properties indicat
 - [uiSchema={}]: UiSchema<T, S, F> - The UI schema from which to derive potentially displayable information
 - [rootSchema]: S | undefined - The root schema, used to primarily to look up `$ref`s
 - [globalOptions={}]: GlobalUISchemaOptions - The optional Global UI Schema from which to get any fallback `xxx` options
+- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf&lt;S&gt; - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_custommergeallof) prop
 
 #### Returns
 
@@ -936,6 +937,7 @@ The closest match is determined using the number of matching properties, and mor
 - options: S[] - The list of options to find a matching options from
 - [selectedOption=-1]: number - The index of the currently selected option, defaulted to -1 if not specified
 - [discriminatorField]: string | undefined - The optional name of the field within the options object whose value is used to determine which option is selected
+- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf&lt;S&gt; - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_custommergeallof) prop
 
 #### Returns
 
@@ -985,6 +987,7 @@ Checks to see if the `schema` and `uiSchema` combination represents an array of
 - schema: S - The schema for which check for array of files flag is desired
 - [uiSchema={}]: UiSchema<T, S, F> - The UI schema from which to check the widget
 - [rootSchema]: S | undefined - The root schema, used to primarily to look up `$ref`s
+- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf&lt;S&gt; - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_custommergeallof) prop
 
 #### Returns
 
@@ -999,6 +1002,7 @@ Checks to see if the `schema` combination represents a multi-select
 - validator: ValidatorType<T, S, F> - An implementation of the `ValidatorType` interface that will be used when necessary
 - schema: S - The schema for which check for a multi-select flag is desired
 - [rootSchema]: S | undefined - The root schema, used to primarily to look up `$ref`s
+- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf&lt;S&gt; - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_custommergeallof) prop
 
 #### Returns
 
@@ -1013,6 +1017,7 @@ Checks to see if the `schema` combination represents a select
 - validator: ValidatorType<T, S, F> - An implementation of the `ValidatorType` interface that will be used when necessary
 - theSchema: S - The schema for which check for a select flag is desired
 - [rootSchema]: S | undefined - The root schema, used to primarily to look up `$ref`s
+- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf&lt;S&gt; - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_custommergeallof) prop
 
 #### Returns
 
@@ -1048,6 +1053,7 @@ potentially recursive resolution.
 - schema: S - The schema for which retrieving a schema is desired
 - [rootSchema={}]: S - The root schema that will be forwarded to all the APIs
 - [rawFormData]: T | undefined - The current formData, if any, to assist retrieving a schema
+- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf&lt;S&gt; - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_custommergeallof) prop
 
 #### Returns
 
@@ -1067,6 +1073,7 @@ Also, any properties in the old schema that are non-existent in the new schema a
 - [newSchema]: S | undefined - The new schema for which the data is being sanitized
 - [oldSchema]: S | undefined - The old schema from which the data originated
 - [data={}]: any - The form data associated with the schema, defaulting to an empty object when undefined
+- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf&lt;S&gt; - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_custommergeallof) prop
 
 #### Returns
 
@@ -1085,6 +1092,7 @@ Generates an `IdSchema` object for the `schema`, recursively
 - [formData]: T | undefined - The current formData, if any, to assist retrieving a schema
 - [idPrefix='root']: string - The prefix to use for the id
 - [idSeparator='_']: string - The separator to use for the path segments in the id
+- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf&lt;S&gt; - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_custommergeallof) prop
 
 #### Returns
 
@@ -1101,6 +1109,7 @@ Generates an `PathSchema` object for the `schema`, recursively
 - [name='']: string - The base name for the schema
 - [rootSchema]: S | undefined - The root schema, used to primarily to look up `$ref`s
 - [formData]: T | undefined - The current formData, if any, to assist retrieving a schema
+- [experimental_customMergeAllOf]: Experimental_CustomMergeAllOf&lt;S&gt; - See `Form` documentation for the [experimental_customMergeAllOf](./form-props.md#experimental_custommergeallof) prop
 
 #### Returns
 
diff --git a/packages/utils/src/createSchemaUtils.ts b/packages/utils/src/createSchemaUtils.ts
index cfd6883e39..153dd9a000 100644
--- a/packages/utils/src/createSchemaUtils.ts
+++ b/packages/utils/src/createSchemaUtils.ts
@@ -133,7 +133,14 @@ class SchemaUtils<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends Fo
    * @returns - True if the label should be displayed or false if it should not
    */
   getDisplayLabel(schema: S, uiSchema?: UiSchema<T, S, F>, globalOptions?: GlobalUISchemaOptions) {
-    return getDisplayLabel<T, S, F>(this.validator, schema, uiSchema, this.rootSchema, globalOptions);
+    return getDisplayLabel<T, S, F>(
+      this.validator,
+      schema,
+      uiSchema,
+      this.rootSchema,
+      globalOptions,
+      this.experimental_customMergeAllOf
+    );
   }
 
   /** Determines which of the given `options` provided most closely matches the `formData`.
@@ -161,7 +168,8 @@ class SchemaUtils<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends Fo
       formData,
       options,
       selectedOption,
-      discriminatorField
+      discriminatorField,
+      this.experimental_customMergeAllOf
     );
   }
 
@@ -199,7 +207,7 @@ class SchemaUtils<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends Fo
    * @returns - True if schema/uiSchema contains an array of files, otherwise false
    */
   isFilesArray(schema: S, uiSchema?: UiSchema<T, S, F>) {
-    return isFilesArray<T, S, F>(this.validator, schema, uiSchema, this.rootSchema);
+    return isFilesArray<T, S, F>(this.validator, schema, uiSchema, this.rootSchema, this.experimental_customMergeAllOf);
   }
 
   /** Checks to see if the `schema` combination represents a multi-select
@@ -208,7 +216,7 @@ class SchemaUtils<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends Fo
    * @returns - True if schema contains a multi-select, otherwise false
    */
   isMultiSelect(schema: S) {
-    return isMultiSelect<T, S, F>(this.validator, schema, this.rootSchema);
+    return isMultiSelect<T, S, F>(this.validator, schema, this.rootSchema, this.experimental_customMergeAllOf);
   }
 
   /** Checks to see if the `schema` combination represents a select
@@ -217,7 +225,7 @@ class SchemaUtils<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends Fo
    * @returns - True if schema contains a select, otherwise false
    */
   isSelect(schema: S) {
-    return isSelect<T, S, F>(this.validator, schema, this.rootSchema);
+    return isSelect<T, S, F>(this.validator, schema, this.rootSchema, this.experimental_customMergeAllOf);
   }
 
   /** Merges the errors in `additionalErrorSchema` into the existing `validationData` by combining the hierarchies in
@@ -265,7 +273,14 @@ class SchemaUtils<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends Fo
    *      to `undefined`. Will return `undefined` if the new schema is not an object containing properties.
    */
   sanitizeDataForNewSchema(newSchema?: S, oldSchema?: S, data?: any): T {
-    return sanitizeDataForNewSchema(this.validator, this.rootSchema, newSchema, oldSchema, data);
+    return sanitizeDataForNewSchema(
+      this.validator,
+      this.rootSchema,
+      newSchema,
+      oldSchema,
+      data,
+      this.experimental_customMergeAllOf
+    );
   }
 
   /** Generates an `IdSchema` object for the `schema`, recursively
@@ -298,7 +313,14 @@ class SchemaUtils<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends Fo
    * @returns - The `PathSchema` object for the `schema`
    */
   toPathSchema(schema: S, name?: string, formData?: T): PathSchema<T> {
-    return toPathSchema<T, S, F>(this.validator, schema, name, this.rootSchema, formData);
+    return toPathSchema<T, S, F>(
+      this.validator,
+      schema,
+      name,
+      this.rootSchema,
+      formData,
+      this.experimental_customMergeAllOf
+    );
   }
 }
 
diff --git a/packages/utils/src/schema/getClosestMatchingOption.ts b/packages/utils/src/schema/getClosestMatchingOption.ts
index 400ebab75e..3360db3747 100644
--- a/packages/utils/src/schema/getClosestMatchingOption.ts
+++ b/packages/utils/src/schema/getClosestMatchingOption.ts
@@ -10,7 +10,7 @@ import getFirstMatchingOption from './getFirstMatchingOption';
 import retrieveSchema, { resolveAllReferences } from './retrieveSchema';
 import { ONE_OF_KEY, REF_KEY, JUNK_OPTION_ID, ANY_OF_KEY } from '../constants';
 import guessType from '../guessType';
-import { FormContextType, RJSFSchema, StrictRJSFSchema, ValidatorType } from '../types';
+import { Experimental_CustomMergeAllOf, FormContextType, RJSFSchema, StrictRJSFSchema, ValidatorType } from '../types';
 import getDiscriminatorFieldFromSchema from '../getDiscriminatorFieldFromSchema';
 import getOptionMatchingSimpleDiscriminator from '../getOptionMatchingSimpleDiscriminator';
 
@@ -45,13 +45,15 @@ export const JUNK_OPTION: StrictRJSFSchema = {
  * @param rootSchema - The root JSON schema of the entire form
  * @param schema - The schema for which the score is being calculated
  * @param formData - The form data associated with the schema, used to calculate the score
+ * @param [experimental_customMergeAllOf] - Optional function that allows for custom merging of `allOf` schemas
  * @returns - The score a schema against the formData
  */
 export function calculateIndexScore<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends FormContextType = any>(
   validator: ValidatorType<T, S, F>,
   rootSchema: S,
   schema?: S,
-  formData?: any
+  formData?: any,
+  experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
 ): number {
   let totalScore = 0;
   if (schema) {
@@ -64,8 +66,23 @@ export function calculateIndexScore<T = any, S extends StrictRJSFSchema = RJSFSc
             return score;
           }
           if (has(value, REF_KEY)) {
-            const newSchema = retrieveSchema<T, S, F>(validator, value as S, rootSchema, formValue);
-            return score + calculateIndexScore<T, S, F>(validator, rootSchema, newSchema, formValue || {});
+            const newSchema = retrieveSchema<T, S, F>(
+              validator,
+              value as S,
+              rootSchema,
+              formValue,
+              experimental_customMergeAllOf
+            );
+            return (
+              score +
+              calculateIndexScore<T, S, F>(
+                validator,
+                rootSchema,
+                newSchema,
+                formValue || {},
+                experimental_customMergeAllOf
+              )
+            );
           }
           if ((has(value, ONE_OF_KEY) || has(value, ANY_OF_KEY)) && formValue) {
             const key = has(value, ONE_OF_KEY) ? ONE_OF_KEY : ANY_OF_KEY;
@@ -78,7 +95,8 @@ export function calculateIndexScore<T = any, S extends StrictRJSFSchema = RJSFSc
                 formValue,
                 get(value, key) as S[],
                 -1,
-                discriminator
+                discriminator,
+                experimental_customMergeAllOf
               )
             );
           }
@@ -87,7 +105,10 @@ export function calculateIndexScore<T = any, S extends StrictRJSFSchema = RJSFSc
               // If the structure is matching then give it a little boost in score
               score += 1;
             }
-            return score + calculateIndexScore<T, S, F>(validator, rootSchema, value as S, formValue);
+            return (
+              score +
+              calculateIndexScore<T, S, F>(validator, rootSchema, value as S, formValue, experimental_customMergeAllOf)
+            );
           }
           if (value.type === guessType(formValue)) {
             // If the types match, then we bump the score by one
@@ -135,6 +156,7 @@ export function calculateIndexScore<T = any, S extends StrictRJSFSchema = RJSFSc
  * @param [selectedOption=-1] - The index of the currently selected option, defaulted to -1 if not specified
  * @param [discriminatorField] - The optional name of the field within the options object whose value is used to
  *          determine which option is selected
+ * @param [experimental_customMergeAllOf] - Optional function that allows for custom merging of `allOf` schemas
  * @returns - The index of the option that is the closest match to the `formData` or the `selectedOption` if no match
  */
 export default function getClosestMatchingOption<
@@ -147,7 +169,8 @@ export default function getClosestMatchingOption<
   formData: T | undefined,
   options: S[],
   selectedOption = -1,
-  discriminatorField?: string
+  discriminatorField?: string,
+  experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
 ): number {
   // First resolve any refs in the options
   const resolvedOptions = options.map((option) => {
@@ -185,7 +208,7 @@ export default function getClosestMatchingOption<
     (scoreData: BestType, index: number) => {
       const { bestScore } = scoreData;
       const option = resolvedOptions[index];
-      const score = calculateIndexScore(validator, rootSchema, option, formData);
+      const score = calculateIndexScore(validator, rootSchema, option, formData, experimental_customMergeAllOf);
       scoreCount.add(score);
       if (score > bestScore) {
         return { bestIndex: index, bestScore: score };
diff --git a/packages/utils/src/schema/getDefaultFormState.ts b/packages/utils/src/schema/getDefaultFormState.ts
index 580e9f8d98..f367b2cbf0 100644
--- a/packages/utils/src/schema/getDefaultFormState.ts
+++ b/packages/utils/src/schema/getDefaultFormState.ts
@@ -241,6 +241,7 @@ export function computeDefaults<T = any, S extends StrictRJSFSchema = RJSFSchema
         includeUndefinedValues,
         _recurseList,
         experimental_defaultFormStateBehavior,
+        experimental_customMergeAllOf,
         parentDefaults: Array.isArray(parentDefaults) ? parentDefaults[idx] : undefined,
         rawFormData: formData as T,
         required,
@@ -268,7 +269,8 @@ export function computeDefaults<T = any, S extends StrictRJSFSchema = RJSFSchema
         isEmpty(formData) ? undefined : formData,
         oneOf as S[],
         0,
-        discriminator
+        discriminator,
+        experimental_customMergeAllOf
       )
     ] as S;
     schemaToCompute = mergeSchemas(remaining, schemaToCompute) as S;
@@ -285,7 +287,8 @@ export function computeDefaults<T = any, S extends StrictRJSFSchema = RJSFSchema
         isEmpty(formData) ? undefined : formData,
         anyOf as S[],
         0,
-        discriminator
+        discriminator,
+        experimental_customMergeAllOf
       )
     ] as S;
     schemaToCompute = mergeSchemas(remaining, schemaToCompute) as S;
@@ -297,6 +300,7 @@ export function computeDefaults<T = any, S extends StrictRJSFSchema = RJSFSchema
       includeUndefinedValues,
       _recurseList: updatedRecurseList,
       experimental_defaultFormStateBehavior: experimental_dfsb_to_compute,
+      experimental_customMergeAllOf,
       parentDefaults: defaults as T | undefined,
       rawFormData: formData as T,
       required,
@@ -404,6 +408,7 @@ export function getObjectDefaults<T = any, S extends StrictRJSFSchema = RJSFSche
           rootSchema,
           _recurseList,
           experimental_defaultFormStateBehavior,
+          experimental_customMergeAllOf,
           includeUndefinedValues: includeUndefinedValues === true,
           parentDefaults: get(defaults, [key]),
           rawFormData: get(formData, [key]),
@@ -440,6 +445,7 @@ export function getArrayDefaults<T = any, S extends StrictRJSFSchema = RJSFSchem
     rootSchema = {} as S,
     _recurseList = [],
     experimental_defaultFormStateBehavior = undefined,
+    experimental_customMergeAllOf = undefined,
     required,
   }: ComputeDefaultsProps<T, S> = {},
   defaults?: T | T[] | undefined
@@ -465,6 +471,7 @@ export function getArrayDefaults<T = any, S extends StrictRJSFSchema = RJSFSchem
         rootSchema,
         _recurseList,
         experimental_defaultFormStateBehavior,
+        experimental_customMergeAllOf,
         parentDefaults: item,
         required,
       });
@@ -482,6 +489,7 @@ export function getArrayDefaults<T = any, S extends StrictRJSFSchema = RJSFSchem
           rootSchema,
           _recurseList,
           experimental_defaultFormStateBehavior,
+          experimental_customMergeAllOf,
           rawFormData: item,
           parentDefaults: get(defaults, [idx]),
           required,
@@ -513,7 +521,7 @@ export function getArrayDefaults<T = any, S extends StrictRJSFSchema = RJSFSchem
   const defaultsLength = Array.isArray(defaults) ? defaults.length : 0;
   if (
     !schema.minItems ||
-    isMultiSelect<T, S, F>(validator, schema, rootSchema) ||
+    isMultiSelect<T, S, F>(validator, schema, rootSchema, experimental_customMergeAllOf) ||
     computeSkipPopulate<T, S, F>(validator, schema, rootSchema) ||
     schema.minItems <= defaultsLength
   ) {
@@ -531,6 +539,7 @@ export function getArrayDefaults<T = any, S extends StrictRJSFSchema = RJSFSchem
       rootSchema,
       _recurseList,
       experimental_defaultFormStateBehavior,
+      experimental_customMergeAllOf,
       required,
     })
   ) as T[];
diff --git a/packages/utils/src/schema/getDisplayLabel.ts b/packages/utils/src/schema/getDisplayLabel.ts
index c1df81d149..7f7746bdc9 100644
--- a/packages/utils/src/schema/getDisplayLabel.ts
+++ b/packages/utils/src/schema/getDisplayLabel.ts
@@ -9,6 +9,7 @@ import {
   StrictRJSFSchema,
   UiSchema,
   ValidatorType,
+  Experimental_CustomMergeAllOf,
 } from '../types';
 import isFilesArray from './isFilesArray';
 import isMultiSelect from './isMultiSelect';
@@ -21,6 +22,7 @@ import isMultiSelect from './isMultiSelect';
  * @param [uiSchema={}] - The UI schema from which to derive potentially displayable information
  * @param [rootSchema] - The root schema, used to primarily to look up `$ref`s
  * @param [globalOptions={}] - The optional Global UI Schema from which to get any fallback `xxx` options
+ * @param [experimental_customMergeAllOf] - Optional function that allows for custom merging of `allOf` schemas
  * @returns - True if the label should be displayed or false if it should not
  */
 export default function getDisplayLabel<
@@ -32,7 +34,8 @@ export default function getDisplayLabel<
   schema: S,
   uiSchema: UiSchema<T, S, F> = {},
   rootSchema?: S,
-  globalOptions?: GlobalUISchemaOptions
+  globalOptions?: GlobalUISchemaOptions,
+  experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
 ): boolean {
   const uiOptions = getUiOptions<T, S, F>(uiSchema, globalOptions);
   const { label = true } = uiOptions;
@@ -41,8 +44,8 @@ export default function getDisplayLabel<
 
   if (schemaType === 'array') {
     displayLabel =
-      isMultiSelect<T, S, F>(validator, schema, rootSchema) ||
-      isFilesArray<T, S, F>(validator, schema, uiSchema, rootSchema) ||
+      isMultiSelect<T, S, F>(validator, schema, rootSchema, experimental_customMergeAllOf) ||
+      isFilesArray<T, S, F>(validator, schema, uiSchema, rootSchema, experimental_customMergeAllOf) ||
       isCustomWidget(uiSchema);
   }
 
diff --git a/packages/utils/src/schema/isFilesArray.ts b/packages/utils/src/schema/isFilesArray.ts
index 1e7f43451b..9c69020f2e 100644
--- a/packages/utils/src/schema/isFilesArray.ts
+++ b/packages/utils/src/schema/isFilesArray.ts
@@ -1,5 +1,12 @@
 import { UI_WIDGET_KEY } from '../constants';
-import { FormContextType, RJSFSchema, StrictRJSFSchema, UiSchema, ValidatorType } from '../types';
+import {
+  Experimental_CustomMergeAllOf,
+  FormContextType,
+  RJSFSchema,
+  StrictRJSFSchema,
+  UiSchema,
+  ValidatorType,
+} from '../types';
 import retrieveSchema from './retrieveSchema';
 
 /** Checks to see if the `schema` and `uiSchema` combination represents an array of files
@@ -8,19 +15,27 @@ import retrieveSchema from './retrieveSchema';
  * @param schema - The schema for which check for array of files flag is desired
  * @param [uiSchema={}] - The UI schema from which to check the widget
  * @param [rootSchema] - The root schema, used to primarily to look up `$ref`s
+ * @param [experimental_customMergeAllOf] - Optional function that allows for custom merging of `allOf` schemas
  * @returns - True if schema/uiSchema contains an array of files, otherwise false
  */
 export default function isFilesArray<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends FormContextType = any>(
   validator: ValidatorType<T, S, F>,
   schema: S,
   uiSchema: UiSchema<T, S, F> = {},
-  rootSchema?: S
+  rootSchema?: S,
+  experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
 ) {
   if (uiSchema[UI_WIDGET_KEY] === 'files') {
     return true;
   }
   if (schema.items) {
-    const itemsSchema = retrieveSchema<T, S, F>(validator, schema.items as S, rootSchema);
+    const itemsSchema = retrieveSchema<T, S, F>(
+      validator,
+      schema.items as S,
+      rootSchema,
+      undefined,
+      experimental_customMergeAllOf
+    );
     return itemsSchema.type === 'string' && itemsSchema.format === 'data-url';
   }
   return false;
diff --git a/packages/utils/src/schema/isMultiSelect.ts b/packages/utils/src/schema/isMultiSelect.ts
index 04c8a54e68..412a5e6752 100644
--- a/packages/utils/src/schema/isMultiSelect.ts
+++ b/packages/utils/src/schema/isMultiSelect.ts
@@ -1,4 +1,4 @@
-import { FormContextType, RJSFSchema, StrictRJSFSchema, ValidatorType } from '../types';
+import { FormContextType, RJSFSchema, StrictRJSFSchema, ValidatorType, Experimental_CustomMergeAllOf } from '../types';
 
 import isSelect from './isSelect';
 
@@ -7,15 +7,21 @@ import isSelect from './isSelect';
  * @param validator - An implementation of the `ValidatorType` interface that will be used when necessary
  * @param schema - The schema for which check for a multi-select flag is desired
  * @param [rootSchema] - The root schema, used to primarily to look up `$ref`s
+ * @param [experimental_customMergeAllOf] - Optional function that allows for custom merging of `allOf` schemas
  * @returns - True if schema contains a multi-select, otherwise false
  */
 export default function isMultiSelect<
   T = any,
   S extends StrictRJSFSchema = RJSFSchema,
   F extends FormContextType = any
->(validator: ValidatorType<T, S, F>, schema: S, rootSchema?: S) {
+>(
+  validator: ValidatorType<T, S, F>,
+  schema: S,
+  rootSchema?: S,
+  experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
+) {
   if (!schema.uniqueItems || !schema.items || typeof schema.items === 'boolean') {
     return false;
   }
-  return isSelect<T, S, F>(validator, schema.items as S, rootSchema);
+  return isSelect<T, S, F>(validator, schema.items as S, rootSchema, experimental_customMergeAllOf);
 }
diff --git a/packages/utils/src/schema/isSelect.ts b/packages/utils/src/schema/isSelect.ts
index 1be32b670c..741912a2ab 100644
--- a/packages/utils/src/schema/isSelect.ts
+++ b/packages/utils/src/schema/isSelect.ts
@@ -1,5 +1,5 @@
 import isConstant from '../isConstant';
-import { FormContextType, RJSFSchema, StrictRJSFSchema, ValidatorType } from '../types';
+import { FormContextType, RJSFSchema, StrictRJSFSchema, ValidatorType, Experimental_CustomMergeAllOf } from '../types';
 import retrieveSchema from './retrieveSchema';
 
 /** Checks to see if the `schema` combination represents a select
@@ -7,14 +7,16 @@ import retrieveSchema from './retrieveSchema';
  * @param validator - An implementation of the `ValidatorType` interface that will be used when necessary
  * @param theSchema - The schema for which check for a select flag is desired
  * @param [rootSchema] - The root schema, used to primarily to look up `$ref`s
+ * @param [experimental_customMergeAllOf] - Optional function that allows for custom merging of `allOf` schemas
  * @returns - True if schema contains a select, otherwise false
  */
 export default function isSelect<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends FormContextType = any>(
   validator: ValidatorType<T, S, F>,
   theSchema: S,
-  rootSchema: S = {} as S
+  rootSchema: S = {} as S,
+  experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
 ) {
-  const schema = retrieveSchema<T, S, F>(validator, theSchema, rootSchema, undefined);
+  const schema = retrieveSchema<T, S, F>(validator, theSchema, rootSchema, undefined, experimental_customMergeAllOf);
   const altSchemas = schema.oneOf || schema.anyOf;
   if (Array.isArray(schema.enum)) {
     return true;
diff --git a/packages/utils/src/schema/retrieveSchema.ts b/packages/utils/src/schema/retrieveSchema.ts
index af837512ac..17439cf396 100644
--- a/packages/utils/src/schema/retrieveSchema.ts
+++ b/packages/utils/src/schema/retrieveSchema.ts
@@ -365,13 +365,20 @@ export function resolveAllReferences<S extends StrictRJSFSchema = RJSFSchema>(
  * @param theSchema - The schema for which the existing additional properties is desired
  * @param [rootSchema] - The root schema, used to primarily to look up `$ref`s * @param validator
  * @param [aFormData] - The current formData, if any, to assist retrieving a schema
+ * @param [experimental_customMergeAllOf] - Optional function that allows for custom merging of `allOf` schemas
  * @returns - The updated schema with additional properties stubbed
  */
 export function stubExistingAdditionalProperties<
   T = any,
   S extends StrictRJSFSchema = RJSFSchema,
   F extends FormContextType = any
->(validator: ValidatorType<T, S, F>, theSchema: S, rootSchema?: S, aFormData?: T): S {
+>(
+  validator: ValidatorType<T, S, F>,
+  theSchema: S,
+  rootSchema?: S,
+  aFormData?: T,
+  experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
+): S {
   // Clone the schema so that we don't ruin the consumer's original
   const schema = {
     ...theSchema,
@@ -393,7 +400,8 @@ export function stubExistingAdditionalProperties<
           validator,
           { $ref: get(schema.additionalProperties, [REF_KEY]) } as S,
           rootSchema,
-          formData as T
+          formData as T,
+          experimental_customMergeAllOf
         );
       } else if ('type' in schema.additionalProperties!) {
         additionalProperties = { ...schema.additionalProperties };
@@ -456,7 +464,8 @@ export function retrieveSchemaInternal<
     rootSchema,
     expandAllBranches,
     recurseList,
-    rawFormData
+    rawFormData,
+    experimental_customMergeAllOf
   );
   return resolvedSchemas.flatMap((s: S) => {
     let resolvedSchema = s;
@@ -507,7 +516,13 @@ export function retrieveSchemaInternal<
     const hasAdditionalProperties =
       ADDITIONAL_PROPERTIES_KEY in resolvedSchema && resolvedSchema.additionalProperties !== false;
     if (hasAdditionalProperties) {
-      return stubExistingAdditionalProperties<T, S, F>(validator, resolvedSchema, rootSchema, rawFormData as T);
+      return stubExistingAdditionalProperties<T, S, F>(
+        validator,
+        resolvedSchema,
+        rootSchema,
+        rawFormData as T,
+        experimental_customMergeAllOf
+      );
     }
 
     return resolvedSchema;
diff --git a/packages/utils/src/schema/sanitizeDataForNewSchema.ts b/packages/utils/src/schema/sanitizeDataForNewSchema.ts
index cd07eea930..c1ab83c7b8 100644
--- a/packages/utils/src/schema/sanitizeDataForNewSchema.ts
+++ b/packages/utils/src/schema/sanitizeDataForNewSchema.ts
@@ -1,7 +1,14 @@
 import get from 'lodash/get';
 import has from 'lodash/has';
 
-import { FormContextType, GenericObjectType, RJSFSchema, StrictRJSFSchema, ValidatorType } from '../types';
+import {
+  Experimental_CustomMergeAllOf,
+  FormContextType,
+  GenericObjectType,
+  RJSFSchema,
+  StrictRJSFSchema,
+  ValidatorType,
+} from '../types';
 import { PROPERTIES_KEY, REF_KEY } from '../constants';
 import retrieveSchema from './retrieveSchema';
 
@@ -51,6 +58,7 @@ const NO_VALUE = Symbol('no Value');
  * @param [newSchema] - The new schema for which the data is being sanitized
  * @param [oldSchema] - The old schema from which the data originated
  * @param [data={}] - The form data associated with the schema, defaulting to an empty object when undefined
+ * @param [experimental_customMergeAllOf] - Optional function that allows for custom merging of `allOf` schemas
  * @returns - The new form data, with all the fields uniquely associated with the old schema set
  *      to `undefined`. Will return `undefined` if the new schema is not an object containing properties.
  */
@@ -58,7 +66,14 @@ export default function sanitizeDataForNewSchema<
   T = any,
   S extends StrictRJSFSchema = RJSFSchema,
   F extends FormContextType = any
->(validator: ValidatorType<T, S, F>, rootSchema: S, newSchema?: S, oldSchema?: S, data: any = {}): T {
+>(
+  validator: ValidatorType<T, S, F>,
+  rootSchema: S,
+  newSchema?: S,
+  oldSchema?: S,
+  data: any = {},
+  experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
+): T {
   // By default, we will clear the form data
   let newFormData;
   // If the new schema is of type object and that object contains a list of properties
@@ -82,10 +97,22 @@ export default function sanitizeDataForNewSchema<
       let newKeyedSchema: S = get(newSchema, [PROPERTIES_KEY, key], {});
       // Resolve the refs if they exist
       if (has(oldKeyedSchema, REF_KEY)) {
-        oldKeyedSchema = retrieveSchema<T, S, F>(validator, oldKeyedSchema, rootSchema, formValue);
+        oldKeyedSchema = retrieveSchema<T, S, F>(
+          validator,
+          oldKeyedSchema,
+          rootSchema,
+          formValue,
+          experimental_customMergeAllOf
+        );
       }
       if (has(newKeyedSchema, REF_KEY)) {
-        newKeyedSchema = retrieveSchema<T, S, F>(validator, newKeyedSchema, rootSchema, formValue);
+        newKeyedSchema = retrieveSchema<T, S, F>(
+          validator,
+          newKeyedSchema,
+          rootSchema,
+          formValue,
+          experimental_customMergeAllOf
+        );
       }
       // Now get types and see if they are the same
       const oldSchemaTypeForKey = get(oldKeyedSchema, 'type');
@@ -104,7 +131,8 @@ export default function sanitizeDataForNewSchema<
             rootSchema,
             newKeyedSchema,
             oldKeyedSchema,
-            formValue
+            formValue,
+            experimental_customMergeAllOf
           );
           if (itemData !== undefined || newSchemaTypeForKey === 'array') {
             // only put undefined values for the array type and not the object type
@@ -154,10 +182,22 @@ export default function sanitizeDataForNewSchema<
       !Array.isArray(newSchemaItems)
     ) {
       if (has(oldSchemaItems, REF_KEY)) {
-        oldSchemaItems = retrieveSchema<T, S, F>(validator, oldSchemaItems as S, rootSchema, data as T);
+        oldSchemaItems = retrieveSchema<T, S, F>(
+          validator,
+          oldSchemaItems as S,
+          rootSchema,
+          data as T,
+          experimental_customMergeAllOf
+        );
       }
       if (has(newSchemaItems, REF_KEY)) {
-        newSchemaItems = retrieveSchema<T, S, F>(validator, newSchemaItems as S, rootSchema, data as T);
+        newSchemaItems = retrieveSchema<T, S, F>(
+          validator,
+          newSchemaItems as S,
+          rootSchema,
+          data as T,
+          experimental_customMergeAllOf
+        );
       }
       // Now get types and see if they are the same
       const oldSchemaType = get(oldSchemaItems, 'type');
@@ -172,7 +212,8 @@ export default function sanitizeDataForNewSchema<
               rootSchema,
               newSchemaItems as S,
               oldSchemaItems as S,
-              aValue
+              aValue,
+              experimental_customMergeAllOf
             );
             if (itemValue !== undefined && (maxItems < 0 || newValue.length < maxItems)) {
               newValue.push(itemValue);
diff --git a/packages/utils/src/schema/toIdSchema.ts b/packages/utils/src/schema/toIdSchema.ts
index 1265cd8af8..21cb334517 100644
--- a/packages/utils/src/schema/toIdSchema.ts
+++ b/packages/utils/src/schema/toIdSchema.ts
@@ -41,7 +41,7 @@ function toIdSchemaInternal<T = any, S extends StrictRJSFSchema = RJSFSchema, F
   experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
 ): IdSchema<T> {
   if (REF_KEY in schema || DEPENDENCIES_KEY in schema || ALL_OF_KEY in schema) {
-    const _schema = retrieveSchema<T, S, F>(validator, schema, rootSchema, formData);
+    const _schema = retrieveSchema<T, S, F>(validator, schema, rootSchema, formData, experimental_customMergeAllOf);
     const sameSchemaIndex = _recurseList.findIndex((item) => isEqual(item, _schema));
     if (sameSchemaIndex === -1) {
       return toIdSchemaInternal<T, S, F>(
diff --git a/packages/utils/src/schema/toPathSchema.ts b/packages/utils/src/schema/toPathSchema.ts
index e0b2abb368..d29f225e5a 100644
--- a/packages/utils/src/schema/toPathSchema.ts
+++ b/packages/utils/src/schema/toPathSchema.ts
@@ -15,7 +15,15 @@ import {
   RJSF_ADDITIONAL_PROPERTIES_FLAG,
 } from '../constants';
 import getDiscriminatorFieldFromSchema from '../getDiscriminatorFieldFromSchema';
-import { FormContextType, GenericObjectType, PathSchema, RJSFSchema, StrictRJSFSchema, ValidatorType } from '../types';
+import {
+  Experimental_CustomMergeAllOf,
+  FormContextType,
+  GenericObjectType,
+  PathSchema,
+  RJSFSchema,
+  StrictRJSFSchema,
+  ValidatorType,
+} from '../types';
 import getClosestMatchingOption from './getClosestMatchingOption';
 import retrieveSchema from './retrieveSchema';
 
@@ -28,6 +36,7 @@ import retrieveSchema from './retrieveSchema';
  * @param [rootSchema] - The root schema, used to primarily to look up `$ref`s
  * @param [formData] - The current formData, if any, to assist retrieving a schema
  * @param [_recurseList=[]] - The list of retrieved schemas currently being recursed, used to prevent infinite recursion
+ * @param [experimental_customMergeAllOf] - Optional function that allows for custom merging of `allOf` schemas
  * @returns - The `PathSchema` object for the `schema`
  */
 function toPathSchemaInternal<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends FormContextType = any>(
@@ -36,10 +45,11 @@ function toPathSchemaInternal<T = any, S extends StrictRJSFSchema = RJSFSchema,
   name: string,
   rootSchema?: S,
   formData?: T,
-  _recurseList: S[] = []
+  _recurseList: S[] = [],
+  experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
 ): PathSchema<T> {
   if (REF_KEY in schema || DEPENDENCIES_KEY in schema || ALL_OF_KEY in schema) {
-    const _schema = retrieveSchema<T, S, F>(validator, schema, rootSchema, formData);
+    const _schema = retrieveSchema<T, S, F>(validator, schema, rootSchema, formData, experimental_customMergeAllOf);
     const sameSchemaIndex = _recurseList.findIndex((item) => isEqual(item, _schema));
     if (sameSchemaIndex === -1) {
       return toPathSchemaInternal<T, S, F>(
@@ -48,7 +58,8 @@ function toPathSchemaInternal<T = any, S extends StrictRJSFSchema = RJSFSchema,
         name,
         rootSchema,
         formData,
-        _recurseList.concat(_schema)
+        _recurseList.concat(_schema),
+        experimental_customMergeAllOf
       );
     }
   }
@@ -60,11 +71,27 @@ function toPathSchemaInternal<T = any, S extends StrictRJSFSchema = RJSFSchema,
   if (ONE_OF_KEY in schema || ANY_OF_KEY in schema) {
     const xxxOf: S[] = ONE_OF_KEY in schema ? (schema.oneOf as S[]) : (schema.anyOf as S[]);
     const discriminator = getDiscriminatorFieldFromSchema<S>(schema);
-    const index = getClosestMatchingOption<T, S, F>(validator, rootSchema!, formData, xxxOf, 0, discriminator);
+    const index = getClosestMatchingOption<T, S, F>(
+      validator,
+      rootSchema!,
+      formData,
+      xxxOf,
+      0,
+      discriminator,
+      experimental_customMergeAllOf
+    );
     const _schema: S = xxxOf![index] as S;
     pathSchema = {
       ...pathSchema,
-      ...toPathSchemaInternal<T, S, F>(validator, _schema, name, rootSchema, formData, _recurseList),
+      ...toPathSchemaInternal<T, S, F>(
+        validator,
+        _schema,
+        name,
+        rootSchema,
+        formData,
+        _recurseList,
+        experimental_customMergeAllOf
+      ),
     };
   }
 
@@ -84,7 +111,8 @@ function toPathSchemaInternal<T = any, S extends StrictRJSFSchema = RJSFSchema,
             `${name}.${i}`,
             rootSchema,
             element,
-            _recurseList
+            _recurseList,
+            experimental_customMergeAllOf
           );
         } else if (schemaAdditionalItems) {
           (pathSchema as PathSchema<T[]>)[i] = toPathSchemaInternal<T, S, F>(
@@ -93,7 +121,8 @@ function toPathSchemaInternal<T = any, S extends StrictRJSFSchema = RJSFSchema,
             `${name}.${i}`,
             rootSchema,
             element,
-            _recurseList
+            _recurseList,
+            experimental_customMergeAllOf
           );
         } else {
           console.warn(`Unable to generate path schema for "${name}.${i}". No schema defined for it`);
@@ -107,7 +136,8 @@ function toPathSchemaInternal<T = any, S extends StrictRJSFSchema = RJSFSchema,
           `${name}.${i}`,
           rootSchema,
           element,
-          _recurseList
+          _recurseList,
+          experimental_customMergeAllOf
         );
       });
     }
@@ -122,7 +152,8 @@ function toPathSchemaInternal<T = any, S extends StrictRJSFSchema = RJSFSchema,
         // It's possible that formData is not an object -- this can happen if an
         // array item has just been added, but not populated with data yet
         get(formData, [property]),
-        _recurseList
+        _recurseList,
+        experimental_customMergeAllOf
       );
     }
   }
@@ -136,6 +167,7 @@ function toPathSchemaInternal<T = any, S extends StrictRJSFSchema = RJSFSchema,
  * @param [name=''] - The base name for the schema
  * @param [rootSchema] - The root schema, used to primarily to look up `$ref`s
  * @param [formData] - The current formData, if any, to assist retrieving a schema
+ * @param [experimental_customMergeAllOf] - Optional function that allows for custom merging of `allOf` schemas
  * @returns - The `PathSchema` object for the `schema`
  */
 export default function toPathSchema<T = any, S extends StrictRJSFSchema = RJSFSchema, F extends FormContextType = any>(
@@ -143,7 +175,8 @@ export default function toPathSchema<T = any, S extends StrictRJSFSchema = RJSFS
   schema: S,
   name = '',
   rootSchema?: S,
-  formData?: T
+  formData?: T,
+  experimental_customMergeAllOf?: Experimental_CustomMergeAllOf<S>
 ): PathSchema<T> {
-  return toPathSchemaInternal(validator, schema, name, rootSchema, formData);
+  return toPathSchemaInternal(validator, schema, name, rootSchema, formData, undefined, experimental_customMergeAllOf);
 }