and at all buffet restaurants, he was not charged (and we didn't use any credits) and he ate from the buffet or the family style plates.
At sit down, menu style restaurants, if I ordered something for him, I paid OOP for it. If he was willing, he would eat off my plate and perhaps I would order him a drink if needed. In most cases, he either fell asleep in the stroller or wasn't hungry (his usual state) so we had no trouble.
When ordering CS, we never ordered 3 meals for 3 people. Too much food. We usually used 1 of our CS for breakfast and used 2 for lunch for the four of us (me, dh, ds#1-then 7, and ds#2, then 2.5). He never took more than 3 bites of anything so I would generally eat the balance and we would order something like the bacon double cheeseburger at Pecos Bill's for dh and ds#1 plus get an extra bun. With the toppings bar they both had enough to share and ds#2 and I would share.
You'll be fine. Don't worry.