Not sure if you did this or not, but what we do when we are traveling with a group is have our agent put all the reservation numbers on our file then he contacts the cruise line prior to sailing to have them arrange for dinner seating for all of us using all of the reservation numbers. Never had an issue. If you ever go back to Cozumel, I recommend Paradise Beach. It's a short cab ride from the pier and they have LOADS of amenities. Google Paradise Beach for their direct website.