Hey Estelle-
I am so glad you came to the Disney Parks Moms Panel. What an amazing trip you are planning for 48 teens, 7 adults spending one day in the Magic Kingdom Park. This sounds like pitch for a movie.
When dealing with large groups, Walt Disney World Resort has all your needs covered.
Disney Group Getaways specializes in handling groups needing 10 or more room reservations. A perk for these large groups is special pricing on tickets, recreational activities and dining. If your party is staying one night at a Walt Disney World Resort and visiting Magic Kingdom Park for one day then I would contact Disney Group Getaways.
If you are not staying at a Walt Disney World Resort then you have
several options which are explained very well by my fellow panelist, Jackie. The American Automobile Association (AAA) is another place to check for discount tickets. Third party brokers and authorized resellers like AAA may save you a few dollars but the most reliable option is through Walt Disney World Ticketing. You may reach them at (407)-WDISNEY (934-7639).
I hope this helps you plan a magical day for your group. Please let me know if I can answer any other questions.
Enjoy making many Magical Memories!
~Jason °O°