Rich Man, Poor Man (1976)

S9E15 Brothers & Sisters

After Mayor West ties the knot with Lois' sister, Carol, they decide to move into the Griffin household, aiming to create a united "happy" family. This shift means Stewie has to vacate his room and move into Chris' space, but not everyone is unhappy with the new arrangement. Meanwhile, Peter and Mayor West hit it off and develop a close friendship.