Kids won’t stop fighting, and it’s getting violent

I am posting on behalf of a friend who doesn’t have Reddit. This isn’t about my children, my friend is just desperate for advice right now.

Her kids are 7M, 9M, 11F, 13F, and 16M. She is a single mom who left her abusive husband 3ish years ago (he has not had contact with the kids since). She also has two adult children 18F and 20F who appear to be well adjusted and normal as far as young adults go.

The kids are CONSTANTLY fighting over everything. They scream, swear, throw things, hit, pull hair, kick, threaten, insult, and have even told each other several times “I hope you die” or “go hang yourself”. No specific kid is starting the majority of the arguments, they all do it about equally, and it’s almost always about stuff that doesn’t even matter like one of them walking past another too closely.

Their mom doesn’t believe in spanking or yelling at her kids, but she also doesn’t really know what to do for consequences for behavior. If a kid is put in a time out, they’ll just walk away when they feel like it. When they’re told to do a chore, they say no and refuse to do anything helpful. Following them to try and get them to actually do it just pisses them off, and the kid usually ends up throwing stuff or screaming/swearing.

16M sneaks out often, and is caught every time thanks to the doorbell camera. He refuses to say where he goes or what he does, and his phone has no evidence of anything. He’s grounded but that hasn’t stopped him. His phone was taken away but he takes it from his mom’s room at night and leaves anyway.

I love my friend and her kids, but they’ve been getting so much worse lately. They lie about everything constantly and refuse to apologize or take responsibility for anything. They hurt each other verbally and physically for literally no reason, and when asked the youngest two have even said they do it because it’s fun, or they’re bored.

My friend has cried, and begged, and tried her hardest to figure out why they’re acting like this. They always have refused to talk in therapy, and they won’t even go to therapy at all lately. My friend has weekly sessions for herself.

No major life events have happened recently. The kids’ parents are still in the middle of a divorce but they’re not involved in it at all. Their dad was an angry mean guy, but he hasn’t been in their lives for 3 years now and they’ve only been acting like this for the past year or so, and it’s only gotten really bad in the last 3 months. The older two kids just avoid the other kids because they can’t deal with the craziness anymore. These kids have friends, but none of them seem like bad influences or have bad home lives or anything.

She’s at a loss and I want to help, but she asked for advice today and I couldn’t think of anything.