ABC’s Once Upon a Time will shed light on two differently evil sisters during the back half of Season 5 — and to that end has cast tweenage Regina and Zelena.

TVLine has learned that Ava Acres, who recurs on Crazy Ex-Girlfriend (as Young Rebecca) and who also memorably haunted Agents of S.H.I.E.L.D.’s Melinda May during the Cavalry’s backstory, has been cast in Episode 19 as Young Regina.

English actress Isabella Blake-Thomas (BBC’s The Green Balloon Club), meanwhile, will play Young Zelena in the same episode, which is titled “Sisters.”

Seen at age 10, Regina is described as neglected and lonely, with zero interest in her mother’s royal duties. Twelve-year-old Zelena meanwhile is coming to terms with the magical ability her father despises so much.

Barbara Hershey — who returns as Cora in the winter premiere (airing March 6) — likely will appear in the episode as the girls’ shared mother.

As previously scooped by TVLine, though Zelena was banished back to Oz in the midseason finale, she will resurface in Season 5B — in part, to battle a warrior-mode Dorothy Gale (Chicago Fire alum Teri Reeves).

“[Zelena] is absolutely not done,” co-creator Eddy Kitsis recently told TVLine. “The Zelena story in Oz, with Dorothy, will tie into our Underworld story pretty significantly.”

Are you curious to see what the half-sisters were up during their tweenage years?