Welcome back to the Disney Parks Moms Panel, Monique!
I am so glad you came to us to ask your question about your Very Merry Christmas cruise with so many families! Once everyone is actually booked on the same cruise, it is extremely simple to link all of the reservations together.
You will need to call my friends at the Disney Cruise Line Reservation desk at 800-449-3380. When you call, please be sure to have each family's reservation number (or numbers). Ask your agent to please link all of the reservations. They will then ask you for the numbers. You will know this is complete when you log into your cruise reservation at the DCL
website. You will see everyone's names show up for booking Port Adventures, Spa, or Adult Dining.
I have done this numerous times in the past so that we could dine with our friends. We have never had an issue. There is a possibility that you will have multiple tables to dine at in the main dining rooms, but the servers will not mind if you switch at each meal.
I hope this helps with your cruise planning! Please let us know if you have more questions that arise as your voyage gets closer.
Happy Cruising, Tracy V.