Closing PO for drop ship orders

I understand that Sage 100 considers a PO closed if the ordered quantity = received quantity = invoiced quantity.  

Our customer does 100% of their orders as drop ships.  When the shipping documents arrive, including the invoice, they use the "receipt of invoice entry" function to post the invoice.  The invoiced quantity is updated to reflect the receipt, but the received quantity does not, so how does the PO ever get closed?

They also need to "force" the PO to close sometimes due to a short shipment that will never be fulfilled.  Same question, how to get the PO to close?