SAP discontinue process issue with use-to-exhaust

Question

SITUATION
Current discontinue functionality in SAP allows a user to automatically shift demand to part B when inventory for part A is projected to be exhausted. Example:
Part A on hand is 240
Demand is 100/week
Part A inventory will run out in week 3
Demand for 60 in week 3, and for all part A demand in week 4 and beyond, will appear against part B.
This can be a great tool when all demand for part A is being replaced by part B, it avoids having to maintain an effective date on every parent BOM that contains part A.
COMPLICATION
This is inadequate for typical situations in which we plan to use up part A before moving to part B. There is usually a lead time to obtain part B, often the same or similar to part A. We need to cover demand with part A through that lead time, which usually involves consuming all part A inventory plus part A open PO’s, which cover demand through that lead time.
The user will probably want to get part B as soon as possible, and close or reduce any open PO’s for part A no longer needed based on when part B will be available. But in most cases, some part A PO’s will be needed to cover demand until part B can be received.
RECOMMENDATION
Discontinue functionality in SAP should provide at least the option to consume part A inventory and open purchase orders before shifting part A demand to part B.
We may have a projected shortage inside the part A PO horizon. That should trigger an expedite of a part A PO, not shift demand to part B.
Please advise if there are any workaround for system to consider open purchase orders for part A before shifting the demand to part B?
Thank you.

Answer 1

There is an effective out date field too in MRP4.
I think if your planned independent requirements for the FG are outside this date then the replacement material will form as part of BOM explosion.
for e.g if the eff out time is oct30 and your PIR of FG is 1st nov. the BOM explosion of that requirement will have part b as plan order or PR, means you will have a PR for the new part, even as the current consumption is for the original part.