Communication between different instances of SAP HR

We have a situation: HR and the rest of the SAP modules including CATS are resided in different SAP instances....

We are trying to maintain all employee and contractor data in a centralized SAP HR system and send the bare minimum employee and contractor data to another SAP system via ALE to facilitate the CATS data entry. We have particular problem with contractor in HR system, specifically in info type 0315, where the PO information is not available in central HR instance. Do you have any solution on this issue? We hope to avoid entering employee data in one system and contractor data in another system. We are in SAP 4.6C.

You could potentially run a daily Batch session, where you are updating one instance and sending all information for IT315 to the overall instance. I would need more information on this; however, my first thought is to run the batch session to update records.