When Marge starts losing hair due to stress, the Simpsons hire a nanny, Shrrry Bobbins (not to be confused with Marry Poppins). She binds the family together and helps them to become functional, mostly through musicals. But just when everything is going right she leaves and then Marge starts losing her hair again, so she stays.
Soon Sherry starts to give up herself because the Simpsons didn't learn anything. But the family explain with a song that they want to stay the way there are, and Sherry flies away.