Welcome back Carter

After Peter catches Lois' dad, Carter, having an affair, he is strong-armed into keeping a secret. But when Peter accidentally spills the beans, Lois' mom demands a divorce, and Peter is in charge of Carter's return to bachelorhood.
this episode was also the first episode excluding stewie in the story, since the character who plays stewie also plays several other main characters you can only assume thet the reason for not including a baby in the episode is most likely to point out the effect that marital issues can have on children.