PO: Business flow - How to acheive from front end

Hi All,

Initally the PO was in approved status .
The user realised that the PO should'nt be created on this supplier.
But by the time he realized this , the PO was partially received .
Then the user Unreserved the PO and Cancelled the PO and then he was trying to do the RTV,Now system is not allowing as it has been cancelled ie Cancelled flag is "YES" and PO status is "Requires Reapproval"

Actually the user should have done the RTV first and then should have cancelled the PO.
now business is asking , how to overcome this from Front end only.