Is there a standard way to flag a purchase order for manual invoice verification so that we can verify that the appropriate documentation has been provided (attached) with the invoice? For example, we have a service provided in the field and the goods receipt is performed to timely book the cost. However, we don't want to allow the automatic payment of the invoice until we validate that included with the invoice was documentation that isn't available until after the work is performed and comes from the supplier's back-office. We want the invoice workflow to notify a person to verify the appropriate documentation was attached and then that person can release the invoice to be queued for payment.
You can try modifying your Invoice Reconciliation approval workflow to add a mandatory approver with the reason "verify invoice documentation". That would stop the IR from fully reconciling once the "PO Received Quantity Variance" invoice exception is auto-cleared upon the GR.
You can either base your condition on:
If your requirement is to allow users to optionally require manual invoice verification (e.g., if you can't rely on CommodityCode to accurately drive that condition) then maybe the best option is to create a custom field/dropdown on the PO header.