Probably not. The cars are not very wide. Make sure someone with long hair doesn't sit in the seat in front of you or their hair will be hanging down into your food. :-(
I think that might depend on size: me, ds8 and dd2 sat in one row and it was a little close. and dd is a little busy body!!
we always make daddy sit alone!!
It would probably be too crowded for comfort for two adults and an older child all in one seat. Most people watch the movie so there is little talking duirng the meal, anyway.
I ate there with my 2 kids (8 and 10) and the kids sat together in the driver's seat while I sat alone in the middle seat. We had a mom and her ds be our hitchhikers shortly after we were seated.
I would think you could, depending on size of course, here are a couple of pics of my kids being kids of course at the sci-fi, not great pics but you can see the space. I think the kids were, 20, 13, 17
It's not possible to reserve the front row when making reservations, but when you get there you could probably tell the hostess you'd be willing to wait for a front row seat.