Sister, Sister is the fifteenth episode of the fourth season of Good Luck Charlie. It aired on October 13, 2013.
Main Plot: Teddy tries to repair the fractured friendship of Amy and her sister Jamie.
Sub-Plot A: PJ tries to invite a girl from his cooking class over for a project, but ends up having to invite Winnie over instead.
Sub-Plot B: Gabe and Jake, who recently used photographs of Toby to earn money to attend a monster truck rally, worry that Gabe's father will find out.
- First appearance of Jamie, Amy's sister.
- Jamie is played by Leigh-Allyn Baker in a wig.
- Bob Diddlebock is mentioned yet again, along with the fact that Amy dumped him to date Bob Duncan.
- Charlie has the fewest lines of any immediate family member in this episode (not including Toby)
- Winnie, PJ's friend from cooking class, returns and appears to have a crush on PJ.
- The stiuation with Bob Diddlebock and Bob Duncan is similar to Artie Ziff and Homer Simpson from The Simpsons: Marge dates Artie briefly, but ends up breaking up with him to date Homer. Artie later becomes extremely rich and successful, while Homer remains unintelligent and only slightly succesful.
- Three actors wear wigs in this episode.
- Beau does not appear in an episode for the third time in a row.
- This episode includes a flashback from the episode Take Mel Out to the Ball Game.
- Gabe comments on how high his voice used to be, a reference to how the actor's voice has changed over the course of the series.
- Sub-Plot B is closely related to the events of Take Mel Out to the Ball Game, except with a funny twist.
- This is the second time we see Leigh-Allyn Baker with different hair. The first time was in Futuredrama.
- The name of this episode may be a refencre to the tv show Sister Sister.
- Bridgit Mendler as Teddy Duncan.
- Leigh-Allyn Baker as Amy Duncan/ Jamie.
- Bradley Steven Perry as Gabe Duncan.
- Mia Talerico as Charlie Duncan.
- Eric Allan Kramer as Bob Duncan.
- Jason Dolley as PJ Duncan.
- Logan Moreau as Toby Duncan.
- Tucker Albrizzi as Jake.
- John Ross Bowie as Walter.
- Mark Cirillo as Concierge.
- Kevin Covais as Victor Deleseur.
- Marieve Herington as Winnie.
- Jonathon Ryland as Chef.