Prevent a header level promo from applying twice

I have created a promotion that adds an item to the order if the order type is X.  The item is added to the order at the booking phase, and I want it to be applied only once.

When I book the order, the item applies.  But when I query the order and add a line to the order and save, the promo applies again as the order gets rebooked with the new line.

I tried an incompatibility group and and it did not make a difference.  The new order line generates the new promo item added again.

Ideas?  I can only apply this promo item once per order and must prevent it from applying a second time.