My company is an electronics company that purchases PCB's from outside vendors. We receive the boards in QC and buy them off as they get tested. This works quite well for our purposes.  
 
We also get a board that requires a heat sink to be put on (via a work order that changes the part number) before it can ever be tested. This creates a problem when using our standard QC model. I will attempt to explain how we are doing this.
 
We receive in the board (part number 1) into QC. We generate a W.O. to apply the heat sink which pulls PN 1 from stock (driving UOH negative due to the boards being in QC) and creates PN 2 (as UOH). PN 2 gets tested and bought off as PN 1. This is extremely awkward and creates quite a few problems.
 
Ideally we would receive PN 1 into UOH, then create a W.O. to create PN 2 in QC, to be bought off as tested. Is this possible? If so, how? If not, what other suggestions do you have?
 
Hopefully that makes some sense. Thanks for your help.

Yeah that's what we're gonna do. Its not perfect, but it should work.