The Walshes plan to spend the holidays in Hawaii, but their plane experiences mechanical problems. They are forced to fly back to Los Angeles and make an emergency landing. Dylan receives a surprise visit from Suzanne Steele, his father's former lover, and her 12-year-old daughter. The duo recently lost its home in Iowa to a flood, and decided to take a road trip as a distraction. Suzanne reveals that Erica is Dylan's half-sister. He is initially skeptical, but decides to give them the benefit of the doubt. Kelly boycotts Mel's Christmas party, but he comes through for her when she has a dental emergency. David gives Donna the cold shoulder for refusing to sleep with him. He breaks up with her on Christmas Eve. Music: ""This Christmas""; ""The Christmas Song"" by Aaron Neville; ""Jingle Bells""; ""Silver Bells""; ""Angels We Have Heard on High,"" performed by church choir; ""Jingle Bell Rock""; ""Santa