Sage 100

v2014 Enter a master sales order, one line item, qty 100 units. Create a standard sales order for 15 units referencing the master order. Invoice the order for 20 units. Master order shows ordered to date 15, balance 85. I am reasonably sure this is WAD. Is there any way to change this behavior? This is dangerous for companies that over ship orders depending what is available in the warehouse. Preferably, if the master order is for 100 and the invoice is for 20 then the balance would be 80. I know they can go back into the sales order and change the quantities but that is time consuming and prone to errors.

Perhaps a script on the SO detail to update quantity ordered, if the shipped quantity ever goes higher? (I'd test that though because I've had many issues with scripts running during the posting process).

I know a script is an option. I was hoping there was an out of the box option I didn't know about.