Moq its not a problem at all. You are pre-paying for your meals. Its really as if you bought your food on Friday and eat at home except you’re not eating at home, you’re eating in the restaurant. Im not addressing anything done in the restaurant on shabbos. There should be a mashgiach. But again, they can do anything you would do at home, if you hired help for shabbos. Or if you were making shabbos sheva brochos in a hall with a caterer and waiters.