(CBR) - "Once Upon a Time" fans have been clamoring for more details since "Frozen"'s Elsa was teased in the Season 3 finale. ABC already answered some questions with the announcement of Georgina Haig as Elsa and Elizabeth Lail as Anna, but how do they fit into the world of the fantasy drama?

TVLine spoke with co-creator Adam Horowitz about exactly that. First he explained the residents of Storybrooke haven't heard of "Frozen" because of the show's unique time frame. The show "occurs in a semblance of real time," Horowitz said. "We calculated that we are now living in the early part of 2013." "Frozen" didn’t premiere until Nov. 27 of that year.

Horowitz also explicitly stated that the "Frozen" gang will not harbor mysterious, secret familial relationships with the existing characters. "We will go on record as saying that we are not going to reveal that, for example, Elsa is somebody’s sister," Horowitz said.

"Once Upon a Time"'s "Frozen" arc will span the first 11 episodes of the fourth season, which premieres Sept. 28.

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