I am at my wits's end for how to stop the fighting between my 14 yr old stepdaughter and my almost 4 yr old daughter. My stepdaughter is with us every other week, and until recently things were pretty good with her. My 4 year old doesn't misbehave much when her big sister is away. With the fighting, it seems they are both to blame. They cannot play together at all without a fight. One taunts the other and it just escalates into screaming and sometimes hitting from the younger one. Then they both run to tattle on each other. (I have caught the teenager trying to annoy or slyly hurting her little sister.) I am confused how to discipline this equally because of the huge age difference. How can they act so similar??!! I read about the 3-strike system in the books, would it work here?