Hi Kristy!
I love how proactive you are being with your planning!
You absolutely can book your
Walt Disney World Resort vacation package now and update a Guest later if needed.
Based on current guidelines, you will need to modify your reservation at least 30 days before your check-in date to avoid additional charges, if you book a
vacation package.
Clearly, if you book airline reservations, there may be change fees or other additional fees.
If and when you make a change, you might be able to move any
FastPass+ selections you have made from your mom to your dad.
There are a couple of phone numbers I'm going to give you in case you do need to make a change. If you do modify your Guest list, be sure to have your reservation confirmation number available when you call and chat with a Cast Member.
To modify your Guest list, contact Disney Resort Hotel Reservations at (407) 939-1936.
As soon as you make the change, contact a Cast Member on the Internet Help Desk. These friendly experts will do all they can to assist with transferring FastPass+ selections. Their number is (407) 939-4357.
Regardless of whether you go with your mom or your dad, I love that you will be spending time with one of them! What a magical way to spend your vacation at Walt Disney World Resort!
Thanks so much for sharing your question with the Disney Parks Moms Panel. Please let me know if you need any further information as you plan your 2020 Walt Disney World Resort vacation!
Kari