I would set some ground rules. Remind them you are all together because you are friends. Let them know this is time to enjoy each others company. I would also tell them that if you show up incapaciated (drunk), you will be ask to leave and explain it is for safety only. I would also ask them to try to have patience with each other and not bickering. Explain you would like for it to be a "round robin" and the hostess would provide lunch, or brown bag it, that would be fun. If you are all friends, they will understand.