Hiya Jean - welcome to planDisney!
Mickey's Very Merry Christmas Party is one of my favorite things to experience at Walt Disney World Resort around the holiday season. All the decorations, food, entertainment, and festivities are just what I need to get into the holiday spirit!
Tickets for Mickey's Very Merry Christmas Party are unique and thus do not have the same Terms and Conditions as regular Theme Park Tickets. They are date-specific, pricing and availability vary by date, and for these reasons, these tickets are nontransferable and nonrefundable.
While that's the technical answer to your question (i.e., tickets can't be modified), Mickey understands that planning isn't always a cakewalk and that mistakes do happen. I can't make any guarantees, but I recommend
reaching out and speaking to a Cast Member by calling 407-939-5277. You can explain your situation and see what options might be available. This is a very popular event, so I recommend reaching out as soon as possible. If there
is the possibility to correct your mistake, it would only be an option if the correct date still has tickets available, and that can change quickly!
I know this isn't the answer you were hoping for, Jean, but I hope it puts you on the right track. During your trip don't miss the
EPCOT International Festival of the Holidays if you have room for more holiday cheer!
Ryan J.