How are you integrating multiple P6 schedules in OPC and importing updates without losing logic?

Curious,

What is the best way to integrate multiple projects in OPC (Program) and importing schedule updates without losing logic ties to other sub-project schedules?

For example, the construction schedule is tied to commissioning and validation sub-schedules under a Program. Automation schedule would feed into the Commissioning schedule. When I receive a GC schedule update how would you recommend importing the GC schedule so the logic ties to the sub-project remain but any change within the GC schedule is also updated?

Asking for a P6 EPPM scheduler on my project not use to OPC. He keeps reporting import issues.

Thanks!