Stepsibling

A stepsibling or stepsib is the offspring of one's stepparent. This would constitute a stepsister (or stepsis) and a stepbrother (or stepbro).

Culture
In fairy tales, stepsiblings and half-siblings can but need not take after their mother. In Cinderella, the ugly sisters are the main character's stepsisters. Mother Hulda also features wicked stepsisters and The Wonderful Birch a wicked half-sister, but The Rose-Tree and The Juniper Tree feature loving half-siblings, and Kate Crackernuts loving stepsisters. Many romance novels feature heroes who are the stepbrother of the heroine. The step-relationship generally stems from a marriage when the hero and heroine are at least in their adolescence. Some family films and television sitcoms feature a nuclear stepfamily including siblings as the center premise. In many cases, the stepfamily is large and full of children causing situations such as sibling rivalry, rooming, falling in love, and getting along amongst the children as popular plotlines. The stepfamily premise dates back as far as the 1968 film Yours, Mine and Ours. This film gave way to a classic family television sitcom about a blended family known as The Brady Bunch. Some contemporary family sitcoms have made the blended family sitcom more popular with the TGIF show Step by Step bringing about other shows such as Aliens in the Family, Life with Derek, Drake & Josh, and the short lived NBC family sitcom Something So Right. The Life of Riley is a 2009 British comedy television series, shown on BBC One & BBC HD. It focuses on the lives of a blended family. Kevin and Kell is a comic strip that focuses on a blended family. The Disney Channel animated series Phineas and Ferb also prominently features a blended family, chosen by co-creator Jeff "Swampy" Marsh in part due to its underuse in children's programming, and his personal experiences growing up in such a family.