If a customer order 100 pieces.
I create a sales order.
I create an invoice.
He Pays.
I then create a package (packing list)
I need the ability to indicate that he is now getting 80 and then I need the system to remind me that I owe him 20.
So the packing list should have the ability for me to enter how many I am actually packing, against how many was ordered. Then the delta should show as still open and needed to ship.
Otherwise, how am I supposed to know what I still owe a customer.
Also, a packing list should show what is inside the box, not just what was ordered.