The Willoughbys by Lois Lowry

From chapters.ca:
Abandoned by their ill- humored parents to the care of an odious nanny, Tim, the twins, Barnaby A and Barnaby B, and their sister, Jane, attempt to fulfill their roles as good old- fashioned children. Following the models set in lauded tales from "A Christmas Carol" to "Mary Poppins", the four Willoughbys hope to attain their proscribed happy ending too, or at least a satisfyingly maudlin one. However, it is a unquestionably ruthless act that sets in motion the transformations that lead to their salvation and to happy endings for not only the four children, but their nanny, an abandoned baby, a candy magnate, and his long-lost son too. Replete with a tongue- in- cheek glossary and bibliography, this hilarious and decidedly old- fashioned parody pays playful homage to classic works of children's literature.