'Parks and Recreation': Annabeth Gish cast as Ben's sister

The Wyatt family just keeps getting bigger on "Parks and Recreation." And the newest member of the family will be Ben's sister, played by Annabeth Gish.

Gish, best known for parts in TV shows like "The X-Files" and films like "Mystic Pizza," will appear as Stephanie Wyatt in an episode scheduled to air later this season (as first reported by EW.com).

Leslie Knope (Amy Poehler) and fiance Ben (Adam Scott) will meet up with Stephanie in the Wyatts' hometown of Partridge, Minnesota. Although this town has been discussed many times on "Parks and Recreation" -- that's the town that Ben was briefly the mayor of when he was 18 -- this will be the first look at Ben's roots. Filming of the episode begins next week.

Viewers have already met Ben's divorced parents (played by Jonathan Banks and Glenne Headly) at Ben and Leslie's rather problematic engagement party, so the introduction of a sister to the mix is just another step toward the altar. Should be an interesting one.

"Parks and Recreation" airs Thursdays on NBC.