Hello Alice! Welcome to the Disney Parks Moms Panel.
The backstage tours are a wonderful way to immerse yourself in the magic of Walt Disney World Resort and see the "other side" of the world's greatest vacation destination.
I took
Disney's Keys to the Kingdom Tour last year and loved getting to see how all of the magic comes together to make all of the show work onstage. Unfortunately, Disney's Keys to the Kingdom Tour is only available to Guests 16 years of age or older, so your son will have to wait a few years for that experience.
The tour I believe you are referring to is Backstage Magic, a
7-hour in-depth look behind-the-scenes at attractions and entertainment across the entire Walt Disney World Resort. Based on your inquiry, please note that backstage magic takes place at various locations across all of Walt Disney World Resort property and not just in Magic Kingdom.
I can find no policy for Guests switching in the middle of the tour based on a single purchase for a tour and it has never happened in my experience. Guests are welcome to leave the tour and I have seen Guests not participate for the entire duration. Having said that, the Backstage Magic Tour would be a difficult tour to arrange a switch as it transports tour guests to various locations throughout Walt Disney World Resort.
When making reservations for the Backstage Magic Tour by calling (407) 939-8687, inquire with your Tour Specialist whether or not a switch is possible. Perhaps something can be arranged?
If I did not explain the correct tour, or if you have any further inquiries, feel free to write back and I will do all I can to assist you in finding the perfect tour for your vacation.
Good luck!
~Todd