We have a setup with 1 parent company and 7 child companies. Many of our users work on projects for different child companies. Though how can you assign issues or tasks in projects if the user is signed in to another child company?

Example: User A works for Child company X,Y and Z User B works for Child company X,Y and Z

User A is working on a project for company X on Monday User B is working on a project for company Z on Monday

Now user B would like to assign a taks to user A, which he can complete on Wednesday. But with the multiple company setup, user A is not available to select for the task until he signs into Company Z.

Is there a solution for this or is the configuration wrong?