Currently if you create a many-to-many relationship between msdyn_project and aad_users entities (i.e. to have some users assigned to a project as a customisation), and then you'd like to extend the Information form of the Project entity with a subgrid component, which would allow you to add users to a project, the behaviour of the subgrid component is counter-intuitive:

• if you don't assign any AAD Users to a project, then the sub grid shows all the possible AAD Users that are found in the directory - this is misleading for the application users which might think that all the users are assigned to a project
• in fact, on the data level (dataverse), the connection is correct and there are no users assigned to the given project
• if the project gets at least one AAD User assigned, then the subgrid behaves correctly, displaying only the users that were assigned to the very msdyn_project record.

The idea would be that the subgrid component does not show any users in the list if there are none assigned to the given project.

We have got the confirmation from Microsoft Support that this current behaviour is OOTB right now and could be changed in the future, if there are enough votes for the idea.