Yes, trying to save aggregate data instead of calculating when needed is problemmatic. How to make sure the adjustment is not posted repeatedly? Adjustment for new order item and revised order item. Very, very tricky. Maybe the AfterUpdate event of product quantity. Can't remember discussions in all your threads. Have you used the OldValue property of data controls (textbox, combobox, listbox, etc)? In the AfterUpdate event of quantity, if Value is different from OldValue then adjust product inventory and set Post field to true. Then there is the deletion of order item (this is another pitfall for allowing edit of transactions and saving aggregate data) that will also require an adjustment of inventory.