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You’ll probably recognize most of the characters in this exclusive poster for Disney’s new animated short Frozen Fever that’s playing ahead of Cinderella starting on Friday. But Frozen favorites Elsa, Anna, and Olaf are joined by some new personalities you’re going to want to get to know: Those tiny snowmen at the bottom called “snowgies.”

Frozen Fever is the highly anticipated sequel-of-sorts to Disney’s massive 2013 Oscar-winning hit that’s now the highest-grossing animated movie of all time. Fever picks up with our Frozen family as snow queen Elsa plans a surprise birthday party for her spirited sis Anna. The only hitch in their plans? Enchanted Elsa has a cold, and when she sneezes, out pops the snowgies. The characters started out as “mini Olafs,”explains Fever producer Peter Del Vecho. “We realized we wanted Olaf to remain pure, so quickly it evolved into these fun little snowballs we call ‘snowgies’ that bring a lot of mischief and fun to the short.”

For the Fever team, the Frozen phenomenon has never quite stopped. They went straight to work on the short film during Frozen’s worldwide release. “The movie finished opening in Japan in March [2014], and suddenly we’re back in it with the short,” says Del Vecho. “It’s really hard for us to try to define it,” says co-director Chris Buck. “It’s just as much of a surprise, in a good way, to us as it is to everyone. It just keeps going and going.”

The whole short almost centered on the summer-lovin’ snowman Olaf until the filmmaking team — including original Frozen director Jennifer Lee — hit on the idea of magical sniffles. “We could see some different opportunities for some fun and that just got all of us going,” Buck tells Yahoo Movies. From there, they added Anna’s birthday celebration as the emotional heart of the story. “Elsa’s never really been able to throw a party for Anna. They were apart most of their growing up,” he says.

Watch the Frozen Fever trailer:

Once the script was in place, getting the gang —including Kristen Bell as Anna and Josh Gad as Olaf — back into the recording booth to revisit their roles was mostly easy, except for some special scheduling around Idina Menzel (Elsa) and her Broadway obligations for the musical If/Then. “Everyone was still riding the high of the movie and couldn’t wait to get back,” says Del Vecho.

Lucky for the filmmakers, Bell was pregnant again during recording just as she was during the first movie. “Her voice actually changes when she’s pregnant,” Buck says, referencing the fact that Bell had to re-record certain lines for the first installment. He jokes, “If we do another Frozen, she’s just going to have to have another baby. No pressure.”

Both Buck and Del Vecho echo co-director Lee’s recent statements, confirming there are no plans yet for a feature-length sequel to Frozen. Fans can still look forward to the Broadway version in 2017 with a handful of new songs. “You need to musicalize a lot of the moments that were in the film because you don’t have the epic nature of cinematography,” says Del Vecho. And then there’s always the endless stream of fan-made Frozen videos on YouTube. “If we don’t get one almost every day, it is rare,” says Buck. “It’s amazing.”

Get a special look at Frozen Fever: