Buyer Ability to Update Requisition

Hello Gurus,

I have a requirement as below:

Requirement:

Buyer needs an ability to update Requisition under his queue.

Once requisition is approved and lands in buyer queue, buyer needs authorization to update certain fields like Qty, Price, Need By Date, Deliver to Location, Copy, Delete.

This is requirement for both Requisitions, Approved and ready for buyer to convert to PO, also a requisition which is converted to PO.

Am also aware of requisition Change Request, but it is limited to requisition preparer and not to a Buyer.

Am also aware of Mass update program for both requisition and Purchase, but this is not the feasible solution.