GDevelop does not allow me to place or remove objects within a variant of a custom object

[QuetzalcoutlDev]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hi, I'm having a strange problem with the engine that I can't easily explain, but for some reason, GDevelop won't let me add new objects within a new variant of an existing object.

Here's a video showing what I mean.

simplescreenrecorder-2026-01-08_17.48.40.mp4

I'm working on an extension to improve the dialog tree functionality, but the issue is that, seemingly out of nowhere, GDevelop won't let me add or remove children of the custom object when creating a new variant.

I've even shown that even with a prefab like PanelSpriteButton (which isn't part of my extension), I can't add or remove objects in the new variant.

(I'm not sure if I made myself clear, but I don't speak English well and I use a translator so I may not have explained myself correctly)

Steps to reproduce

1. Create a new variant of a prefab object

GDevelop platform

Desktop

GDevelop version

5.6.251

Platform info

Details

OS (e.g. Windows, Linux, macOS, Android, iOS)

Linux

OS Version (e.g. Windows 10, macOS 10.15)

Linux Mint 22.2

Additional context

This didn't always happen; it started out of nowhere. I don't think it's that serious, but it's so strange I don't know if it's a problem on my end or with the engine.

Because within the default version I created in the extension, it does allow adding new objects.

Although now I'm wondering, has it always been like this?

[4ian]

If I'm not mistaken, it has always been like this: the reason is that the custom object must have a single set of "child objects", because all the variants of the custom objects share the exact same events. So if an object exist in a variant, it must exist in all of them.
This being said, it's totally possible for a variant to make no use of one or more objects.

In other words, the main variant of your custom object should have all the possible objects that can be used by variants (and the events handle them). Then variants can have instances of all of them or only some, as needed.

Let me know if that make sense? We should probably have a paragraph about it in the documentation @D8H

[D8H]

You can edit objects from here:

[QuetzalcoutlDev]

@4ian It must be a misunderstanding on my part, I'm sure I have a faulty memory.

The thing is, it would be good if the GDevelop documentation clarified some things that are confusing or lack explanation, such as with prefab objects.

[QuetzalcoutlDev]

@D8H The confusion stems from my belief that once the prefab object is configured, new objects can be added to it when adding it to a scene outside of the extension using a new variant.

[4ian]

I've added a paragraph about it on the custom object page on the documentation: https://github.com/GDevelopApp/GDevelop-documentation/pull/411/changes - I hope this can help (at least it makes clear this is a "limitation", but one that is expected) (though we could probably find a way in the interface to tell "hey if you need a new object here, please add it to the default variant")

[D8H]

We could maybe allow object additions from any variant for extensions that are created by users themselves.

[QuetzalcoutlDev]

@4ian The whole point of an extension is to prevent the developer from having to modify it to suit their needs, so I acknowledge my confusion and will instead look for a better way to create the extension to make using DialogTree easier for creating narrative games (like visual novels) with GDevelop.

Thank you for answering my question, and I apologize for any inconvenience caused by my confusion 😅