Autumn and Allen: Oh they love Christmas, so they would probably start to decorate their apartment as soon Halloween finishes: Autumn gets ready to buy a big Christmas tree and get the cutest accessories to hang on it and for the small sister she will buy the chocolate calendar, which every day has got a little snack to eat.
Allen will write a big ass list to Santa Claus with all her wishes: cooler toys, new EG skates, new videogames, a giant lasagna to eat by herself and a music CD with all the funky tunes. Autumn's wallet cries already.

Magalie's family: If we talk about the past, when Wave and Pearl were just lil children, then Magalie and her husband (not Tsunami) would try to be ready when Christmas comes, despite both Mag and the handsome dude are really busy people with their hard job. Christmas gifts were never a problem for this family and you know why. They would spoil their children, or better Magalie spoiled them. Husbando wants to teach them that they need to earn what they ask.
In the present day they just celebrate it with Quiet, now that Wave lives alone or is busy with her criminal business.

Quiet's family: In the past, Quiet had her baby Storm and Jet to take care and spoil for Christams. She's not someone who celebrates it religiousely, but Quiet knows it is important for the children.
Christmas lunch and dinner are probably the best part of the holiday, according to both the hawk and albatross.

Diana: Being a lone "wolf" she doesn't care about celebrating it, but she gets invited by Mag to celebrate it with her anyway. She would cook something delicious for the day to exchange the gesture.

Tempest: She doesn't celebrate it but she gifts herself the best liquor and chills watching the snow from her abandoned ship. Sometimes she remembers the past Christmas times, when she was still "dating" Stream and hanging out with the others. Somehow she liked it and you could get free food and alcohol. Better life didn't exist.

Yves: This anxious Fennec Fox would take 2 weeks from her job and fly back to France to visit her parents and her 4 younger siblings, taking with herself the goodies like food, snacks and other objects exclusive to Soleanna
She celebrates Christmas like a normal family would do!

Anders: He's a ghost, so he can't do much about it. However he observes the living enjoying the holiday and he gets extremely curious on the lights, silly decorations and the music surrounding this event. He's surprised how much money people spend in this time of the year but he wishes he could feel their same joy.