We went in August and there were 3 groups of people, all staying at different resorts. Unfortunately, we had booked separately our hotels (some DVC) and then made it a Grand Gathering. It took us a few months to get an event booked because we kept running into problems linking our reservations.
If you have booked it from the beginning as a Grand Gathering, I would think you wouldn't have the problems we did.
Anyway, we went on the Magical Fireworks Voyage and loved it!!! The kids and adults had so much fun and watching Wishes from the water was even more breathtaking, the music is piped in so you don't miss that part. We did this our last night and it was a great way to end our vacation.
Have a great trip!
Nancy