We never buy kids meals because my kids just don't like them. We just order what my dh and I want (with a thought to what the kids like, too), and then just say "We'll need an extra plate for each of the kids." I've never been to a restaurant, Disney or not, that has a problem with that. If they make a face, which sometimes happens, I just explain that they are small and you never know what a small kid will eat. They almost always agree to that and cheerfully bring the extra plate.
Sometimes at Disney we'll just order an appetizer, one meal, and dessert for the whole family to share, and it is plenty for the 4 of us. I am, however, in possession of the lightest eater on the planet (dd, age 4), and the pickiest boy on the planet (ds 2), and dh and I are both fairly light eaters.