Flowing expected delivery dates through to customer BO reports

Netsuite allows us to build and send out back-order reports for our customers, and in our distribution business this is a vital information source for our customers.  When an order is created the system takes an expected delivery date and attaches it to the item line- if the product is in stock that date is immediate, if its not in stock it takes the date from our expected delivery date from our supplier on our POs.  This date gets reported on our customer backorder report.  So far, so good. 

Unfortunately in distribution, delivery dates from suppliers move, almost always backwards and this is where our problem starts.  If a supplier moves the expected delivery date and notifies us, we can change this date on our PO.  What Netsuite doesn't appear to do is reflect this in the customer's expected delivery date, so the backorder report will only ever show the expected delivery date on the day the order is placed.