When there's a big snow storm outside and a fallen branch cuts off Bart's electronic entertainment, he does to play with Lisa and Maggie, only to get bored and jealous of their sister bond.  After a dream of brothers bonding that includes Peyton, Eli and Cooper Manning throwing around a football, Bart decides he wants a brother and begings a plot to get Homer to impregnant Marge.  After failing to get them to do it and to sabotage her birth control pills, Marge convinces Bart that he could have another sister.  

After a flash forward to Kim Cattral as his third sister, he quickly abandons those plans.  After trying to get a little brother at the Big Brother program, they send him home unsuccessful, only for him to wake up the next date with Charlie, a boy from the orphanage at his house.  He spends the day bonding with Charlie, only for him to get adopted the next day.