My Horrible Sis

When the mother of a ten-year-old Sonya and the father of an eleven-year-old Lena decide to marry, two completely different girls become sisters. Now they have to share the same room, one class and friends, and most importantly, constantly fight for the attention of their parents. Both of them dream of getting rid of another "sister" and get their lives back. Lena and Sonya announce a temporary truce to break up the parents and disrupt the wedding...