Tonnesha, welcome back! You're in the homestretch of counting down the days until you set sail! You're nearly there! How exciting!
I'm really happy to hear that you were able to make reservations for both of your girls at the
Bibbidi Bobbidi Boutique on the Disney Fantasy. My daughter still talks about her makeover there when she was transformed into Snow White. It's a memory your daughters will cherish forever, Tonnesha!
I would try to get a good feel from your girls about which princess they'd like to be over the next couple of weeks and make any changes during that time. There are very limited availability of dresses and sizes once you are onboard since these dresses are chosen ahead of time. Of course, once you are onboard, you can certainly stop into the boutique to ask about the availability of adding components to their makeover, but do try to do that before the appointments so the Fairy Godmothers-In-Training have time to get everything prepared.
My best advice would be to try to stick with the princess dress they choose ahead of time, as it's just not guaranteed that a change of outfit can be made onboard. You are welcome to modify your reservation online or by calling one of the agents at Disney Cruise Line at 800--951-3532 if your daughters decide on a different outfit within the next couple of weeks. Just be sure all changes are made at least 3 days prior to sailing.
Let me know how else I can help before you set sail, Tonnesha!