My customer wants to add a credit-card surcharge based on the payment for a particular snapshot, which is only for the "this delivery" amount.
So on, say, snapshot 2, there is a second payment for the items that were on backorder in snapshot 1, and so we'd like to add a second surcharge.
I was about to tell them 'no', when I decided I had better check...
On a Bill/Complete or Ship+Bill order, you can't add an item to a processed order using the UI, but I don't see a restriction in the code for AddNonInventoryItem.
So is this something a) possible, and b) reasonable, to do in code?