According to Jim Episode 2.11 The Brother-in-Law

Eddie, a country musician who's dating Dana, comes between Jim and his brother-in-law Andy. After hearing Jim and Andy's band practice, Eddie invites them to perform with him at the House of Blues. The catch: Eddie plays keyboards instead of Andy. An excited Jim accepts anyway and hopes to keep the gig a secret from Andy, who, of course, finds out. Encouraged by his sisters, the left-out architect decides to even the score by exploring new business horizons-without his contractor-partner Jim.