Changing a requisition in iProcurement

Changing a requisition that has been assigned to a PO

-         Requisition Modification -> PO Accept Modification (status in Process) -> PO can’t be changed.

How can we improve this process when changes are required?

Clarification:  Even requisitioner cannot modify description or add an attachment when using the “Change” feature in iProcurement.  The only thing that can be modified is the amount.  Support information is almost always necessary when increasing the amount