I am trying to flatten our BOMs.  I don’t want to add unnecessary layers (part#'s) to the BOM and would like to be able to order R type parts and then use some of those same part numbers on WO’s where I can add routings for the in house work.    
 
I want this capability because we are using our Machining dept as a vendor to the production line.  They will be ordered from Machining on a PO using WOPO program.  Machined parts will initially be built to stock, then the parts will be issued to the Welding, painting and assembly work orders.  I just don’t want to add another part number to the original part# to accomplish the built to stock machining tasks.  
 
I can’t see any other way around creating one more level above the R parts to get that intermediate machining done.  Do you have any thoughts that might be a different approach?  Basically we are still looking for best practices that other manufacturers use when trying to flatten the BOM’s.