A woman has 3 daughters with her husband, they split up and she remarries, she then splits up from her second husband and immediately moves in with a male friend and they begin a relationship. The male friend has a son and she has moved all 3 daughters into the home..all children are 6/7-12/13 at this point. When the middle daughter is 17, she has sex with the son who is 19/20 and falls pregnant. Child is born when middle daughter is 18.
At this point they've been all living together as a family for several years and the daughters view male friend as father figure/step dad.