Hi Brenda, welcome to planDisney!
I totally get that plans change! And luckily I have good news! The names assigned to
standard theme park tickets are more to help Guests organize their party members. When you visit the
Disneyland Resort Main Entrance Turnstiles, the Cast Members there will scan your tickets, and take a picture of each Guest. This is how the tickets will be assigned to the Guests. So you can certainly have another person go in place of your sister!
And if you're trying to pick a date to visit, December 2022 still has plenty of reservations available! You can always take a look at the
Theme Park Reservation Availability Calendar to see if the specific day you're interested in has reservations available. Just a reminder, the
Holidays at the Disneyland Resort is currently in full swing through January 8, 2023, so now is a great time to visit!
See ya real soon!
Jin