One-to-many association: wrong (unassociated) items are added to the nested collectionDatasource

[oshiryaeva]

Forum issue
Test project: demo.zip

Environment

• Platform version: 6.10.1
• Database: HSQLDB

Description of the bug

Minimal reproducible example

1. Open demo project
2. Clients > edit a client
3. Click Create, create several projects with and without the reference to the edited client

Actual behavior
ALL projects newly created from the client editor are added to the nested projectsDs datasource of the client editor. All these projects are displayed in the projects table with the wrong client. At the same time, they are saved to DB with the correct client.
If you reopen the client editor, the nested projectsDs datasource will contain only the correct projects.

Expected behaviour
Only the projects with the reference to the edited client are added to the nested projectsDs datasource of the client editor. All others are just saved to the DB.