Did you want to be seated in the cars? I know they have some table seating in back but I’m not sure of how many per table.
Disney goes out of its way to try to make things happen, but it may be a problem not having the number of reservations you need. If you are absolutely committed to eating there, try going to the podium well before your reservation time and see what they tell you.
Five of us had lunch there recently because our daughter-in-law had never experienced it. But I agree with
@Club Cooloholic about it not being a good environment for small kids. Seating in the cars is tight and you can barely see well enough to feed yourself let alone take care of young ones.