Hi, Alanna! One of the reasons I rarely book a character meal breakfast is because my family just doesn't usually eat a big breakfast. While it's wonderful to see the characters, I would much rather see them at lunch or dinner and know that the kids will actually eat something.
Whether or not you will be charged may be up to the individual restaurant managers. When I was recovering from surgery and was on a liquid diet, I was able to enjoy character meals with my family and in most cases was charged a nominal fee for "entertainment". At one restaurant, later on in my recovery, I was charged for a child's meal, but that was with medical documentation of my inability to enjoy a full meal.
If you notify the cast member when you check in that you won't be eating, they should be able to direct the manager to your table. You can inquire as to what they might be able to do to allow you to enjoy sitting there with your family without actually eating anything. But again, this is going to be up to the individual restaurant manager.
Would it work better for you if you try to book meals at another time of day? Then you can actually enjoy the meal too!
Have a great vacation!