The three Wilks sisters in The Adventures of Huckleberry Finn by Mark Twain are MaryJane (age 19), Joanna (age 14), and Susan (age 15).
In the book, the three girls are orphaned when their uncle Peter, their guardian, dies. The King and Duke, two con men who claim to be royalty, work to scam people in the various towns they encounter along the riverbank of the Mississippi. The King and Duke attempt to scam the Wilks sisters by pretending to be their long-lost uncles in order to access the Wilks' inheritance.
When Huck first encounters the King and Duke, he is aware of their true motives but goes along with them to protect Jim. However, when Huck realizes that the two con artists are planning to cheat the Wilks sisters out of their inheritance, he turns on them and ruins their scam.