The CM I spoke with when I was thinking about upgrading my 9 yo to an adult for the plan said that he would be allowed to mix & match if he wanted. My question was about desserts, because DS will want an adult entree, but not the creme brulee, sorbet, or cheesecake that are on most of the adult dessert menus, but I'd imagine it would work the same way for entrees. After all, why would Disney want to discourage people from ordering less expensive kids menu items with their adult credits?