The skin grafts are coded by recipient site and if multiple areas, they are to be grouped in the same code as what the descriptor described for. Example if coding for cheeks and hand you use 15240 if it's more than 20 sq cm you would use the add on code. [see cpt ama book, skin replacement surgery guidelines, pg 110-112]
I would use 15220[scalp] and 15240[hand], but not sure on the sq cm, I would question the provider to include more information so the sq cm can be determined.