The young versions of Kara (Melissa Benoist) and Alex (Chyler Leigh) will look a lot different when Supergirl returns this fall. The adolescent flashback versions of the Danvers sisters have been recast.

Young Kara will now be played by The Fosters' Izabela Vidovic, EW first reported. She will take over for Malina Weissman, who now stars on Netflix's A Series of Unfortunate Events.

The Americans' Olivia Nikkanen is the new young Alex, according to TVLine. She's replacing Jordan Mazarati.

They'll appear in the sixth episode of Season 3, to be called "Midvale." The flashback-heavy episode will follow Kara and Alex as they take a road trip to their childhood home, where they relive a murder mystery from their high school (is this a Riverdale crossover? JK.)

"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 EW.

Melissa Benoist and Chyler Leigh,<em> Supergirl</em>Melissa Benoist and Chyler Leigh, Supergirl

Supergirl returns Monday, Oct. 9 at 8/7c on the CW.

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