I have a crazy idea that may work: On transaction MD09, the same function module which is used to read the planning elements on transaction MD04 is called (AUFBAUEN_MDPSX_ANZEIGEN).
It means that the same BAdIs used on transaction MD04 should be also called in transaction MD09. Therefore, you can try to use BAdI MD_ADD_ELEMENTS to make these orders relevant to MD04 again, so that they can be considered as a pegged requirement.
This may be a complex development and I'm not sure if it will work, but it is worth to try.
BR
Caetano