Hi  PPandIE 

It's difficult to offer advice on a topic as complex as the MRP. So, it will rephrase what I understand in a simple question: how can we use a different list of components (BoM) for a short period of time (to manage products susbtitution due to shortage on the main BoM)?

I suggest to run the MPS (only manufactured products set with MPS) on BOM code 1 (assuming this is the 'normal' BoM code). Then, the planner will tranform the WOS into WO P/F. Doing so, when needed they will manually change the BoM code from 1 into 2 (to care for stock shortage*).

When the planner is done, you can run the MRP (only purchased products set with MRP) using the BoM code 1 again. The trick is to only consider as valid production requirement the MWP / F (not the MWS) and sales of course. Doing so, you are sure the buyer will only procure a component that will follow the planner decision. As a consequence, your planning (WOS -> WO P/F) horizon must be at least as big as your purchasing (POS -> POP/F) horizon.

Note to exclude the MWS linked to a WOS generated by the MPS you need to set the MRP this way:

Same for the MPS.

Note2: if you need to see purchase suggestion (POS) balancing the MWS linked to a WOS (for forecasting or budget purpose), you can try to generate these suggestions via the MPS BUT you must be sure to exclude these suggestions from the planning tools used by the buyer (else you will double your orders). Then the MPS configuration should be:

Don't forget to exclude from the transactions used by the buyer to raise the PO all suggestions generated from the MPS in this case:

* A custom develop upon work order creation can automate the switch from BoM Code 1 to 2 based on the component stock level.