Managing cost of an internally sourced item

Hi

We are on  11.5.10.2 -

Within an operating unit, we have Org B supplying assemblies to Org A.  Both Org A and B use WIP and both are standard costing.  We have BOM's and Routings in Org B and can roll up the costs fine.

My question is:  what is the proper setup and method to maintain the costs for the subassembly in Org A?  (note: we have a few thousand items in this state)

Any help or link to a white paper on this would be greatly appreciated.

thanks

ben