Can someone tell me if I am on the right track with this, please? W/o being able to get into the invoice unless someone pays I can't do it first hand, so it's kind of muddled.
When someone buys an item, and the second one is free s/h, I can adjust the invoice by that amount? Just have $x per item, and deduct $x from the additional items?
Also, what if the pay before getting the invoice?
Thanks!