I have a client who wants to book me for 150 people. He says there might be 175-200 people there but 30 or so of them won't be eating. He wants to pay for 150 that he says will be eating. Now I set up a buffet and let the guests make thier own plates and if they want 2nds let them come back. But how am I going to deterime if 180 are eating instead of 150. It is a bachlor party. How should I handle this?