Enter Receipt in iProcurement without a requisition

Hi

is-it possible to enter receipt in iProcurement related to a PO without requisitions ? 

the business case is described as fellow :

 1. The Buyer enter a PO that concern  multiple requestor in the company  (but requestors don't need to enter requisitions in iprocurement)

 2. requestors contrôle periodically suppliers services related to the PO and want to enter receipt in Oracle iProcurement to allow validating supplier invoices 

(if receipt is not allow in this case using iProcurement, requestors will be obliged to confirm receipts only by emails to buyer that will enter them in Oracle Purchasing)

Thanks.