Adoption, foster homes & Stepparents

I'm always searching for fiction on the theme of adoption/foster homes/stepparents, especially from the child's point of view and I'm wondering if anyone has any recommendations? It can be any kind of book (fantasy, contemporary, historical, whatever) for any age (it doesn't have to be for adults or even young adults, books for younger people are fine as well). It doesn't even have to be the main plot, a subplot works as well. It's simply books dealing with those themes.

Examples (not necessarily from books): Norah McClintock's Chloe and Levesque books, the beginning of the O.C., Anne of Green Gables.