Ahoy, Bossie!
Aren't you excited to cruise down the East Coast for a day at Magic Kingdom and some island fun in the Bahamas? This sounds like a sailing filled with pixie dust to me, and I know your crew can't wait! My family actually sailed this itinerary a few yEARs ago, and we loved cruising out of the Big Apple and being able to experience the Walt Disney World Resort, Castaway Cay and Disney Cruise Line all in one vacation!
Bossie, you've asked an excellent question about how the FastPass+ system will work for your family since you'll be arriving via the Disney Magic. You'll actually receive plastic tickets once onboard that will be pre-loaded with three FastPass+ that can be used at any of the attractions at Magic Kingdom. Doesn't that sound super convenient? Since you already have MagicBands you are welcome to link them to your plastic tickets in
My Disney Experience either on a computer or using the mobile app (internet charges will apply if you want to do this on this ship). If you do link them while on the ship, I would bring the plastic tickets along just to be safe! Once you sign in to your My Disney Experience account, you'll see a spot to link tickets and you'll follow the steps using the numbers on the back of your plastic tickets.
Once you've used your pre-loaded FastPasses, you will be able to see if you can add an additional FastPass+ using the mobile app. Remember, only one can be added at a time, but hopefully you'll find some great options still available.
If you want to book an advanced dining reservation, you can check availability in the
dining section of the Walt Disney World website or by calling (407) 939-3463 just as if you were visiting for a land based stay.
Good luck with your plans!
Nancy