"My Sister's Keeper" is the thirteenth episode of the third season of The Suite Life on Deck and the sixty-second episode overall.
When Woody announces his sister (which both Zack and Cody thought was going to be hideous) will be coming on board, Cody keeps her company, much to the dismay of Woody and Bailey. Meanwhile, London searches for a "twin" to get her to do her dirty work, but things go wrong when her twin falls in love with Zack.
- Phill Lewis as Mr. Moseby
- Matthew Timmons as Woody Fink
- Linsey Godfrey as Willa Fink
- Jane Oshita as London's Double