Hi
How about this option
Currently MRP runs and creates PR for external suppliers.
Option - let MRP run and create normal PR, enhance end of MRP run to PR created to check overstock. If found change the doc type on PR to Intra company STO.
If normal PR has 10, check overstock and change to STO if overstock exists. if overstock less than required qty, then create STO req for available overstock and change qty on normal PR for remaining qty
your thoughts please
thanks
Mahesh