“Once Upon a Time” lovers are head-over-heels obsessed with the ABC show’s casting of “Frozen” characters Elsa and Anna. But fans of the 2013 animated Disney movie are still wondering why leads Kristen Bell and Idina Menzel were not cast in the coveted TV roles. Fortunately, the casting process for the “Frozen” princesses won’t remain a mystery – because co-creators Adam Horowitz and Eddie Kitsis were happy to open up about it.

Speaking with E! Online, Kitsis revealed that they didn’t even go after the stars of Disney’s “Frozen” to offer them the roles. But it wasn’t because they didn’t enjoy them in the animated film. In fact, the creators swore they’re big fans of Bell and Menzel.

“Those actors were so amazing,” Horowitz explained. “But it’s their own thing. They should have their thing, and what we’re doing is separate from the movie. We’re not trying to do a sequel to ‘Frozen.’ We’re trying to do our ‘Once Upon a Time’ version of it and create our own little world and hope that fans of ‘Frozen’ and fans of ‘Once’ can enjoy it.”

As “Once Upon a Time” fans know, the ABC series decided to cast “Fringe” alum Georgina Haig as Elsa, the beautiful princess from Arendelle with the power to create snow, ice and frost. Meanwhile, newcomer Elizabeth Lail was cast as Elsa’s sister, Anna. The TV character is described as “fun-loving, fearless optimist who often gets herself into situations where she is over her head, yet is able to triumph due to her resourcefulness and can-do spirit.”

While Horowitz and Kitsis are attempting a “Once Upon a Time” version of “Frozen,” fans of the movie shouldn’t worry about them straying too far from the original story. Following the Season 3 finale, Horowitz told Entertainment Weekly that they’re looking to “honor what came in the movie.”

“We’re not trying to redefine the character,” Horowitz said of Elsa’s introduction. “What we’re trying to do is take this beloved character and fit her into our world.”

“Once Upon a Time” fans will be able to see that play out through a backstory that will reveal how Elsa ended up in Rumplestiltskin’s vault. Another big question the Season 4 premiere will explore is what Elsa will be up to upon exiting the farmhouse in Storybrooke. But the main concern on everyone’s mind? Will Elsa be good … or evil? Emma’s Jennifer Morrison revealed that she had the same question when she learned that the “Frozen” characters would be joining the show.

“I, as an audience member of the scripts, was totally fascinated to see were they going to be our friends, were they going to be our villains, was the ice going to be a problem, was it not going to be a problem, so I think a lot of the questions that the fans have are questions that we all had,” Morrison told E! “We are now discovering one script at a time the way they’ve put them in our world, and it’s amazing to see how it feels like they’ve always been there.”