Hi there, Lorie!
Every hard-ticket event requires a separate admission, regardless of the type of day ticket used earlier (Annual Pass, Magic Your Way, etc.).
In order to attend the party, each Guest needs to have a wristband; in order to get a wristband, a Guest must present a valid ticket to the evening's event. Without a ticket, the Guest cannot acquire a wristband.
After 7PM, these wristbands will be checked by Cast Members. A Guest without a wristband will be asked to leave the Park.
Your friend will need to purchase her ticket to
Mickey's Very Merry Christmas Party in advance just to ensure that the chosen night is not a sell-out. After that, you two are free to ring in the holidays with Mickey and all of this friends.
Have a wonderful time!
See you later, celebrator,
-Deborah B.