Le Cellier is the most expensive of the group. LTT, CP and Princess Storybook are all buffets, so no sharing. Since the Storybook breakfast is the least expensive I'd plan on paying for that out of pocket. However, since you are doing Sci-Fi and Whispering Canyon before hand which are per item and could be shared, I'd check out the menus for both these places and see what I'd order for the three of you and add it up to see what the amount was and if you'd be making yourself crazy over an insignificant difference of paying for the breakfast out of pocket.
Here's the website to the menu's
http://www.allearsnet.com/din/dining.htm
Portions are a decent size for the kids meals, but if they don't want the same thing and then there is going to be a fight over what to get and about sharing dessert, or having to buy one separately, it might not be worth it.