Brothers

A few months before Lacey, Luna, and Winter's father gets married with their future step-mother, tells her that she should move in with her brothers, only brothers. Winter accepts because she doesn't want to be in the way of her parents during the early honey moon phase, and doesn't want to be rude to her soon-to-be mother.
After the three of them move in with their new step brothers, they start to take a liking in the three sister. But after all, they're only siblings.