After reading a letter in the "Dear Libby" newspaper column, the kids are worried that one of their parents is unhappy with the new kids and is considering leaving the marriage.
Cindy lands the lead role in her school play, but her joy turns to sadness when she discovers that because of a seating shortage she can only invite one parent to the play.
Mike and the boys go on their annual camping and fishing trip, but for the first time with Carol and the girls. However, the trip turns out to be less than peaceful.
After watching "Cinderella," Bobby is convinced that his new mom is an "evil stepmother" and that nobody in his family loves him, so he decides that he will run away from home.
Carol has laryngitis and will not be able to sing at church on Christmas Day, but a department store Santa Claus promises Cindy that she will get her voice back in time.
All six Brady kids have the Measles at the same time, and problems arise when Carol calls in the girls' female pediatrician while Mike brings in the boys' male pediatrician.
Marcia wants to nominate Mike for "Father of the Year." But she wants to keep it a secret, which means she'll have to break family rules to get it done. If she's caught, Mike will punish her--which is exactly what happens.
Since the boys and girls cannot decide on a mutually satisfactory prize, they hold a contest to determine who gets all of the family's combined trading stamps.
Mike worries over a newspaper horoscope, which predicts that a strange woman will enter his life. That woman is a fussy perfume heiress, his firm's latest client who wants her perfume factory impossibly designed to her specifications.
Greg makes an "F" on a math test, and Mike and Carol discover it's because he has a crush on somebody named "Linda." They set out to find out who she is, completely unaware that "Linda" is actually his math teacher.
The kids must handle all the chores when Alice sprains her ankle while Carol is away, but Alice's sprained ankle also means that she will miss the Meat Cutters' Ball with Sam the butcher.
Marcia thinks she is ugly after she gets braces, and it only gets worse when her date to the school dance backs out because his family is going out of town.
Cindy accidentally mixes in Marcia's diary with other books for a book drive. Marcia immediately freaks out, because she's worried that someone else will read it and learn about her secret crush on TV star Desi Arnaz Jr.
The kids think the house is too small for their needs, so Mike decides it's time to sell it. But then the kids have second thoughts and launch a plan to make him change his mind.
Mike believes that teaching the boys how to play baseball is more rigorous than helping Marcia earn her cooking merit badge. Carol believes the opposite is true. Therefore, the two decide to switch roles for the day to prove their point.
Jan gets a locket from a secret admirer. As the family try to determine who anonymously sent the locket, they're momentarily distracted when Jan loses the locket (after the clasp becomes loose and it falls off her).