According to Jim Episode 2.27 Vegas, Baby Part 1

Jim and Andy are going to Vegas on a business trip and ask Dana to join them, since they need an extra help and she happens to be their "rabbit's foot" on gambling. Cheryl decides to join them and blackmails Jim when he says no at first. Cheryl has been secretly in touch with Jim's estranged sister Roxanne and plans for them to meet in Vegas. When they get there, Jim is not pleased to see his sister and tells Cheryl that no matter what she said he's sure she hasn't changed at all. Roxanne says she needs 2.000 dollars to start her business, which Jim takes as the first step on her plan, but Roxanne won't take either his or Cheryl's money. Instead, she gets it from her new husband: Andy, who has fallen head over heels for her and married her while the rest of the family was watching a show.