With Microsoft Dynamics GP 2013 Purchase Order Processing you will be warned if you try to close a purchase order when the quantity invoiced doesn’t match the quantity shipped on the purchase order.

In Edit Purchase Orders each line on the PO will check the quantity shipped and quantity invoiced.  If the quantities don’t match and you try to close the PO line, a warning will be given for the line item.  If you try to close the PO, a warning will be given if one or more lines have quantities that don’t match.  You can continue to close the PO once the warning is given.