"Creating many PO's using same Purchasing Requisition"

Hi Gurus,

How do one configure the system that when once a Purchase Requistion has been used to create a PO, u dont use it anymore, unless u delete the order i know it will be opened for use again, i know when i was still working at Transnet they had it that way. Now here you can create 2PO using one Purchase Requisition.

Secondly, how do you configure the system that it gives you an Error message if you want to create a Standard PO using a Purchase Requisition of Document Type PA(Pojects). Currently it just gives a warning and some people just bypass that warning and eventually we have a wrong PO Number.

I put all my TRUST to The Forum for this Problems.

Regards

Charles