Hi Rebecca!
Welcome to the Disney Parks Moms Panel! I hope you're having fun while planning your unforgettable family vacation with Captain Mickey and his friends! We recently went on a Disney Cruise with my parents, sister and her family. We had such a blast while all being together onboard.
It sounds like your sister joined a Fish Extender exchange group! Fish Extender groups are actually not sponsored by
Disney Cruise Line, but organized by Guests who will be setting sail on the same cruise together! These groups are so fun because, like you said, Guests bring small treats to pass out to other kids and families within the group! To join a group, I recommend going to Facebook and typing the Disney Cruise ship you'll be sailing aboard, as well as your embarkation date, into the search bar. Another place to search for Fish Extender Groups during your upcoming cruise is the popular Disney Cruise Line fan forum, the DisBoards.
We've participated in Fish Extender groups on many Disney Cruise Line adventures and had so much fun giving and receiving treats. Figuring out what you're going to exchange and making or purchasing the treats is a great activity to do with your son leading up to your cruise! It will help make the time pass while you anxiously are counting down the days.
Rebecca, thanks so much for sailing by with this great question! I hope you and your son have an unforgettable high-seas adventure.
Beth