Do you know how to create additional table occurrences of the same table in Manage | Database | Relationships?
Employees::ManagerID = EmployeesByManager::EmployeeID
will provide the relationship you describe. You create EmployeesByManager by selecting Employees in manage | Database
relationships and then clicking the duplicate button (two green plus signs). You can then double click the new occurrence box in order to change the name to something more descriptive than Employees 2 as I've done in the above example.
You may find this tutorial helpful: Tutorial: What are Table Occurrences?
BTW, you have posted this in the portion of FileMaker intended for reporting possible bugs in the software. If you had posted this question in the FM Pro Forum (see tab at top of this screen), you would have gotten a quicker response and possibly from more people.