Can you add more detail on your problem. Are you the owner of the PCB designs? If so, you can just create a multi-layer PCB. With this are associated design considerations. If you're not the owner of the PCB designs, how were you hoping to combine them?

I would combine the two in a multi-layer PCB. I would look up design rules for PCB design across multiple layers. You should find plenty of white documents to help you.