There were 8 of us last summer, including several very picky eaters.
At MK, we ate at the Diamond Horshoe Revue. They serve basic sandwiches, like ham and cheese, but the kids loved the show.
At MGM, we ate lunch at the Backlot Express - typical fast food.
At Epcot, we ate bits and pieces as we visted each country, with everyone sharing. Everyone got to try something new. Most countries have lunch menus that you can eat as you walk. Lunch took us all day!
The best thing you can do before you go is make reservations for dinner. A lot of places have tables for 6 or less and they have to make special arrangements. In some cases, they may have to seat you at two different tables. For three dinners, it took me over an hour with WDW-DINE to make suitable reservations. They were very helpful and patient.
One other thing I did, each child had my cell phone number in their shoe so they could have a cast member contact us if we got separated. Fortunately, no one needed it.
Have a great trip!