You have only one way to do what you need.
The rescheduling program (SDV03V02) behind the V_V2 TCode has been programmed by SAP in a modular way.
The first step retreives the sales/purchase orders and sorts them, the second one do the real job.
So you cano copy the standard program in a custom one, then add your own selection/sort criteria and let the standard program called by the custom one reassign the quantities.
If you’re not able to do this by your own, you can ask to your SAP consultants – like me :-).