I have 2 daughters, Ivy and Lexi. Ivy is 20 months and Lexi is 4 months. My eldest daughter Ivy has started having violent outbursts if she is stopped from doing what she wants to do. She will hit out and even head butt walls. How do I nip this in the bud before it gets worse? I am afraid she might start getting violent with my younger daughter. With them being so close in age I worry that the eldest is jealous of the youngest as she is not getting all the attention now