Reference attributes from different CS

Hi!

I have the following situation: There are two Oracle MA, that imports data from HR-system. The first MA imports persons, the second one imports departments.  It isn't suitable for me to combine them. The department object has an atribute "chiefID", where is set an identifier of the person. So the question is: how can I flow chiefID as Reference atribute? AFAIK, to be able to flow reference attributes - both objects should be in one CS.

Thanks for any help!