The sibling singers have been promoted to series regular status on the ABC country music drama, according to industry trade publication The Hollywood Reporter.
Hailing from Oshawa, Ont., 13-year-old Lennon and 9-year-old Maisy are daughters of country music duo Marylynne and Brad Stella, a.k.a. the Stellas. The youngsters shot to viral video fame with their darling and impressive performance videos on YouTube, where they've earned millions of views.
The sisters were cast to play the daughters of troubled Nashville couple Rayna (Connie Britton) and Teddy (Eric Close) James in the series pilot and continued to pop up throughout the season. In the show's first-season finale, the true paternity of Lennon's character was revealed.
The girls' performances on Nashville have also proved to be hits on iTunes, including the cover of Hey Ho! by the Lumineers that they performed on one episode. They reprised the song at one of several appearances at The Grand Ole Opry.
The second season of Nashville begins in the fall.