By James Hibberd
Updated July 06, 2012 at 07:00 PM EDT
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Christina Applegate is getting a brother on NBC’s Up All Night, a move that’s going to add a major new dynamic to the show.

Actor Luka Jones is joining the comedy as a series regular this fall.

Jones (Best Friends Forever) will play Reagan’s younger brother Scott. He’s a contractor who is great at his job, but ultra laid back and doesn’t have much business sense. He’s a sharp contrast to Applegate’s Reagan, who’s the ultimate planner. Reagan’s husband, Chris (Will Arnett), likes his cool, mellow brother-in-law. The recently divorced Sam also has a five-year-old son who’s given free rein to do whatever he wants, which horrifies Reagan, considering the effect it might have on her daughter. Up All Night returns Thursday, Sept. 20.