Welcome aboard, Sara! Your boys are going to have such an amazing birthday being able to spend it on the Disney Fantasy! I spent my last birthday onboard the Disney Wonder and it was one of the best ones yet!
While I can't guarantee specifics, I will say that Disney Cast Members love to go above and beyond to recognize birthdays or other celebrations onboard. Be sure that you have noted on your reservation that you'll be celebrating your sons' birthdays on this cruise. This info is given to Cast Members, and you never know, they just may surprise your boys with a birthday song at dinner one night.
Do be sure to swing by Guest Services to pick up birthday buttons for your sons. If they wear those buttons, they will draw lots of attention from the Cast Members.
Check out the
GIfts and Amenities page on Disney Cruise Line's website. There you can view gifts that can be ordered to surprise your boys in the stateroom as you arrive. I love the birthday decorations. Just imagine their faces as you walk into your stateroom on that first day onboard and they see that the room is decorated just for them! On that same page you'll see you can pre-order a birthday cake to be presented either at dinner or in your stateroom.
Additionally, you might consider booking a special
Port Adventure for them on their actual birthday. What better way to celebrate than to head off on a special adventure with their family?
Have fun as you continue to plan, Sara, and please let me know if I can help with any other questions before you set sail!