- Go to Invoicing > Configuration > Management > Analytic Items.
- Set the other partner in the form view of an the analytic entry.
- Go back to list view where you can search and group by this new field.
You can also:
- Go to the form view of one of the partners selected as "other partner".
- Click on the smart-button Cost/Revenue placed on the upper-right part.
- Navigate to the analytic items associated to this partner.