One way would be to create a calculation field that holds a list of either
• the processIDs of all processes which have no process manager, OR
• the processIDs of all processes, if staffID is in list of processManagerIDs
Use the field as a match key from Staff into a Processes TO, using that relationship for the conditional VL.
You can calculate the field context-free by using ExecuteSQL; make sure the calculation is set to unstored.