Hi Kelvin, welcome to planDisney!
Thanks for bringing your question to us, I'm happy to help!
Each
theme park ticket needs its own
theme park reservation, so you cannot add additional tickets to a current reservation. You will have to make a separate reservation for each ticket. But I have good news! I just checked the
Theme Park Reservation Availability Calendar and there is full availability at both parks for your arrival date of December 23, 2022.
To make a reservation, you will need to log into your
Disneyland Resort account, select the "My Disneyland" link, and then click the "Ticket and Reservation Details" link. Next, you should see a link that says "Make Park Reservation". Easy right?
If you have any other questions at all, please visit us again!
See ya real soon!
Jin