Oracle creates multiple delivery lines when sales order quantity changed

We are on 12.1.3.

Scenario:

1. If delivery lines are in ready to release status, and sales order line qty is increased, delivery line requested qty is increased.  Good.

2. If delivery is released, customer service must call the warehouse first so the delivery can be back ordered, and then the sale line qty increased.  However, once a delivery line is in back ordered status, if the qty is increased the difference is created as a second delivery line.  This causes us a lot of problems.  Orders are often < then a carton, and then customer wants the carton qty.  So now I get two delivery lines, two pick tasks, each for < than a carton qty in the warehouse when really, it should be a fll carton.  It