In Brothers & Sisters, Lois's unlucky-in-love sister Carol comes for a visit and falls madly in love with Mayor Adam West. Although Lois opposes the marriage because she doesn't want her sister to experience a heartbreak so soon after her ninth divorce, Peter is excited because he's always wanted a brother.
When Carol breaks off the marriage, Mayor West decides to leave Quahog to move to Alaska and Lois decides to support the lovers. Peter convinces Quagmire, who's flying the plane to Alaska to come back to Quahog and Carol reunites with Mayor West.
At the end of the episode, Mayor West and Carol get married and Peter realizes that he now has a sister and a brother.