Confirmation of Work Order (COW)- for Receipts Approval P2P

We have a custom functionality what we call as ''Confirmation of Work Order (COW)'' to ensure if  the services being delivered were confirmed by the Approvers from Management. Generally the Receiver here just makes the receiving based on invoice receipt from vendor and the moment he does receipt entry 2 things happen.

No 1, ''Confirmation of work'' Approval work flow gets triggered and

No 2. Records already in Receipt table which will not prevent AP user from doing voucher match and make a payment without ensuring if the confirmation of work order is approved or not.

We need to restrict AP person from doing a voucher matching for those receipts for which Approval process is not completed but allow him to see those receipts and match them which have been approved by this confirmation of work order cycle. Appreciate any thoughts, inputs