Otherwise it also argue that a FNP can be taken if you lose a wound - in this case, the rule says if you WOULD take a wound. So
its an either-or scenario and only one roll can be taken.
While there's no current FAQ, earlier rulings said that that wasnt possible (albeit on the same model).
To me, its clear in the rules that the Celestian takes the FNP and not the Canoness.