You may not have to choose. We found the CS meals were generous enough to share. In fact I would encourage you to not order a meal for everyone the first time you try a CS meal. We happened to do this our first time and ended up taking a dessert back to the room and all having enough to eat anyway. If you need more food then go back and get that 3rd or 4th meal, but better that way than waste a credit on food you throw away. Once I got the adult breakfast platter(we declined the meats) and shared with our 5yo, we didn't even finish it! I am not the lightest eater and he eats eggs really well.
We used 2 snack credits for Entenmann's donut holes/cinnamon buns in the room so some mornings it may be all you need for breakfast. With a CS adult breakfast you can get two beverages. We usually made them two bottled drinks, one being water that we took to the park, and we rarely finished the juice or milk so we took that back to the room for later. At one CS dinner we got yogurt for dessert and saved it for a quick breakfast the next day. There is lots of flexibility in the plan, enjoy!
As for snacks we used all but one for snacks or beverages. The one odd ball ended up being a waste, she ordered too much food. With two boys I would think you'd want to have those credits available for ice cream, Dole Whips, popcorn, fries, etc. Again you can get some items like that for dessert in your CS meals so just be flexible.
Congrats on your great planning your family should have a magical trip!