Hi David and welcome to the Disney Parks Moms Panel!
I have to admit I'm jealous of your
Highway in the Sky Dine Around reservation. This dining event is definitely on my list of Disney events to try. It sounds like an amazing night of food and drinks culminating in desserts and a private viewing spot of Fireworks over Magic Kingdom Park.
You are correct that typically you would be viewing the Happily Ever After fireworks show but your date falls during
Mickey's Very Merry Christmas Party. Your dining experience will end in the same dessert and beverage offerings with the only difference being you will be viewing the
Holiday Wishes fireworks show. In the "Know before you go" section about the Highway in the Sky Dine Around they do remind you that the event will take place in rain or chilly weather so be sure to be prepared. Florida weather can be a bit unpredictable.
Please let us know if we can help you with any other questions.
Wishing you a magical vacation,
Amy H.