Attitude with teenagers

Alex

I need some advice on my neice. She's a pre-teen, I know she's gonna start going through her puberty changes. But she's had some bad attitude problems. Her parents were talking about it with me and they say they've had enough of her. She gets mad so easily, doesn't listen, hits her sisters for no reason, doesn't help around the house, she's just a handful. Any advice for either of them. How I can help my neice control her anger in a healthy way. She says shes tried breathing exercises, yoga and other stuff. But nothing helps.