The movie I'm looking for is about a family, mother,father and 2sisters. The older sister sneaks back home one morning ans sees the mother having an affair and kills her. The daughter then begins to take up the role as the mother by wearing her clothing and cooking dinners for the father. One night when the father gets in late he falls asleep on the couch and she comes downstairs and they make out on the couch. This movie may have been made in canada. Thank you

Its called Wicked. Julia Stiles is the main character. Great movie.

Or am I wrong and am talking about a completely diff movie? If so, sorry! :)