We order many parts that need modification before they can be used in our primary assemblies.  What I'm trying to do is create a system where unmodified parts don't slip through the cracks and interrupt production.  

For example, we use a gear box that must have precision dual flat spots machined into the shaft.  Let's call the modified gear box item 1234.  Additionally, I also have the unmodified version as 1234-NPP (NPP=Needs Post Processing) which is what the brand new items are received under.  I converted 1234 to an assembly which only has 1234-NPP in the build.

I've then created a new "work order" template for purchase orders (which I call WOPO).  I create the WOPO with our own company as the vendor with Item 1234, who's description is "10:1 Planetary Reducing Gear Box (comes from 1234-NPP)" with a few blank lines and then detailed instructions on how to modify this part.  

I generate the WOPO and add a quantity of 5.  I give it to the machinist and he does his magic.  Once completed, he gives the paper back and -- I thought I could just go to the Receive Items - pick our WOPO and hit save.  However, all this is doing is increasing 1234 and NOT executing the build which would remove 1234-NPP's from our inventory.

Is there some better way to do this??  I understand I can simply close that WOPO then manually execute builds for 1234, but I feel like might be a better way?

Any ideas or feedback are very much welcomed.  Thanks!