Just think of BBQ like an oven or grill for meat!
With that number camping we use to do a buffet type meal.
So you can boil eggs.
Make salad which you buy fresh daily.
Make pasta with pesto/oil or something
Cook chicken, burgers, bacon etc on bbq.
Do you have electric?
Take a toaster and maybe a grill cooker. I always go for electric when camping.
You can do egg or beans on toast.
Cooked breakfast.
We camp with electric and a single ring stove when just ds and I.
We always have toasts, eggs and bacon for breakfast.
Then we don't need a huge packed lunch.
We use to locate the nearest supermarket and buy for that evening meal and following day each evening.
With 7 of you I'd buy roll, ham and cheese and a multipack of crisps. Punnet of grapes, apples and bananas. Also those boxes of brownies or some muffins etc.
Then dinner ^ see above.
Make sure the shopping , cooking and washing up is divided.
If you have kids there they love doing the washing up on campsites but be prepared for them to return wet and covered in bubbles 