Hi Kenneth, welcome to planDisney!
Thanks for bringing your question to us, I can certainly help!
First things first, we'll need to check to see if there is reservation availability for
Disneyland Park on your arrival date of December 29, 2022. I just checked the
Theme Park Reservation Availability Calendar and I have good news! I see availability for Disneyland Park on December 29, 2022, so you should be good to go!
Next step is to cancel your current reservation. Once canceled, you can book your new reservation. There currently isn't a way to change reservations, you have to cancel and book a new one. To cancel, you'll need to log in to your Disneyland Resort account, select the "My Disneyland" link, and then click the "Ticket and Reservation Details" link. Select the reservation you wish to cancel and click "Cancel Reservation". You'll then be able to select the party members who need to cancel. Once canceled, you're free to go ahead and book your new reservation!
Hope this helped, and if you have any more questions, please visit us again!
See ya real soon!
Jin