How do I resolve this reference attribute problem?

We have an Oracle HR table.

EmployeeNumber is unique and is the one we want to use as a base reference.

There is a ReportsTo attribute which contains the EmployeeNumber of the user's manager.

However, To make sense of the data in the table we have to invent an Anchor in our CS consisting of 3 attributes:

EmployeeNumber + OperationType + LastModifiedTime

Having set this anchor, how can I make FIM/MIM use ReportsTo as a reference? Normally I would have set EmployeeNumber as the anchor but is impossible with the table supplied by HR.

I would like to Sync the OracleHR MA ReportsTo attribute to person.MV attribute manager. But How??