Hi Kristy!
I'm so excited for your family! Performing at Walt Disney World Resort or watching a family member do so is such a memorable experience. As a teacher, I travel with teenagers annually for my school's senior trip and I just love seeing my students enjoy The Most Magical Place on Earth with their peers. And I think it's wonderful that your daughter will have the chance to enjoy the theme parks and resorts with you and your son once the band-related portion of the trip concludes.
There are two different ways you could go about adding your daughter to your reservation. If you add her to the vacation package as it currently stands, she would need to have the same tickets, Disney Dining Plan, etc. that you have selected for you and your son. You may not want to do that as I imagine she probably has discounted theme park tickets purchased through the
Disney Youth Program for the days she will be with the band. There's another option that might work better for you. Have you considered splitting your reservation into two parts? It may work nicely if you have just your son and you on the first reservation (covering the days your daughter is with the band), and then have a second reservation for the days when she will be a Guest in your Walt Disney World Resort hotel room. The only downside to the second option is that you may need to switch rooms in the middle of your vacation. However, I'm sure the Cast Members at the front desk will make every effort to keep you in the same room if that is your preference. The upside, of course, is that you are only purchasing entitlements (theme park tickets, etc.) for your daughter on the days she'll need them.
Have a marvelous time watching your daughter perform on your upcoming trip, and don't hesitate to ask additional questions if there's anything you'd like to know about traveling with a school group.
Best wishes,
Jill