Has anyone implemented a 2-way approval workflow similar to this:


We would like some categories (item codes) to be labeled non-fulfillment. 
When an invoice comes in which is tied to a non-fulfillment line, it is put immediately on hold (hold code "pending approval")
An email shoots off to the requester in the Purchase Order with a copy of the invoice with a custom message something like:



Dear Requester on PO XXXXX

We received an invoice from Vendor ABC.  Please let us know if you received the services or software specified on the invoice. If not, please click No and provide comments as to the discrepancies