Hi Shrout1,
I'm assuming your repeating table would have two ID fields. One will get auto-generated when the row is inserted. You can use qRules GuidGen feature for that. GUIDs are better than row IDs since they will migrate across systems as your data moves. Then, define a second field called "Manager" which gets the ID for the manager row. You can select the manager row using a simple xpath filter, something like: my:EmployeeRepeatingGroup[my:EmployeeID = my:ManagerID].
Should be easy. We do this kind of thing all the time.