“Supergirl” has tapped Izabela Vidovic and Olivia Nikkanen to play young versions of the Danvers sisters in a flashback-heavy episode in Season 3 of the CW series.

According to Entertainment Weekly, Vidovic will play young Kara — a role first portrayed by Malina Weissman, who is now a series regular on Netflix’s “A Series of Unfortunate Events.”

Meanwhile, as revealed by TVLine, Nikkanen will appear as high school-aged Alex. In previous flashback scenes throughout the first two seasons of the series, young Alex was played by Jordan Mazarati.

Shortly after news of their casting was announced, both Vidovic and Nikkanen took to Instagram to share how excited they are to be joining the show. Check out their Instagram posts below:

Vidovic and Nikkanen will make their first appearance in Season 3, episode 6, which finds Kara (Melissa Benoist) and Alex (Chyler Leigh) on a road trip to their hometown of Midvale. Upon their arrival, the sisters relive a murder mystery from high school that shaped their relationship.”

“You’ll get to see, through the way they interact, how their relationship started when Kara first came to Earth, how it grew, how it became so close and why they’re so close nowadays,” Benoist told Entertainment Weekly of what fans can expect from the installment, which appropriately titled “Midvale.”

Vidovic is best known for her role as Taylor on Freeform’s “The Fosters” and as Shea Garcia-Miller on NBC’s “About a Boy.” Nikkanen, meanwhile, has appeared in several TV series, including CBS’ “Elementary,” HBO’s “Boardwalk Empire” and CBS-turned-A&E series “Unforgettable.”

The recasting of the young versions of the Danvers sisters comes two months after it was revealed that “Smallville” alum Erica Durance is taking over the role of Alura from Laura Benanti in Season 3. Executive producer Andrew Kreisberg revealed in a statement last July that Benanti won’t be able to continue playing  the role due to her work commitments in New York.

And although Alura has long been dead, executive producer Robert Rovner told Entertainment Weekly that they wanted to keep Alura [in some form] on the show because her presence “connects Kara to Krypton and her roots.” “It’s an emotional grounding that’s always important,” Rovner said.

“Supergirl” Season 3 premieres on Monday, Oct. 9 at 8 p.m. EDT on The CW.