I don't know for sure, but I bet they would be accomodating that way. When DD8 didn't eat all of her entree, they offered several times to bring her out something else. They also let her change her side dish to chips instead of salad.
I will say that you will miss the better dessert though! The blueberry muffin is warm, with a cheesecake filling, and topped with light lemon sorbet that starts melting into the muffin, and drizzled with a slightly tart raspberry sauce...mmmm! Maybe try asking for an extra chocolate crown first, maybe then you can have your "cake and eat it too!"