What is the main conflict in Wives and Daughters by Elizabeth Gaskell?

Wives and Daughters by Elizabeth Gaskell is a novel about young girl named Molly Gibson, who at the age of 17 gets not only a new step mother but also a very beautiful step sister. The novel follows Molly throughout the next couple of years of her life as she adjusts to the new circumstances of her life, and the many challenges it brings with it.