Differ things up a bit and have everyone for breakfast one day and dinner the next. Make them responsible for finding their own meals the rest of the time. If you go to a restaurant, be sure to call ahead of time and inform them of the number in your party, and if they will have any qualms about breaking up the bill or accommodating that many people and how much their going to tack on for the gratuity. An ice cream social is also great on a hot day. I mean masterpiece.
Disposable plates are great, but make sure they're durable.
Cups however, create endless amounts of plastic or Styrofoam and often run out. Use a couple of big tubs or even metal trashcans work great at sealing in the cool. Fill them with ice and pack in plenty of cans or plastic bottles of approximately five different beverages. Remember young children usually never consume their entire drink so put in plenty of small plastic juice bottles too, and don't forget to recycle. Activities Have all the parents submit their old baby pictures and number them.