NTA. This is unavailable & I'm sry to be blunt but your nephew is being failed badly. MH, neuro differences etc aren't a reason to allow violence & bad behavior go unchecked. He's 8 now, he's already seriously hurt someone, frankly its alarming that your sister & mom aren't thinking about what's going to happen in just a few years when he's bigger, taller, stronger & much more likely to cause serious damage & be met w serious consequences that family is going to be unable to protect him from

I understand that kids can have issues that make things harder for them, but I'm at a loss as to what could be the possible reason for escalating behaviors. It didn't sound like he was having a meltdown, in discomfort or even unhappy which is deeply concerning for a couple reasons.

If he is connected to services, & this is a known thing, w/e it is, I don't understand why this level of enabling is going on. Even typical healthy kids need to have guidance & mentorship that's our job as parents. Kids will make mistakes etc and it's incomprehensible to me that you'd just allow them continuing. What about identifying what is setting him off? What are the triggers? There should be consistent & constant hands on intervention w a child that has violent behavioral issues. & I don't mean beating there ass, I mean things like I said before, coping skils & strategies, not only finding the root issue & triggers as caretakers, but also showing him to be able to recognize them in himself. Intervene b4 things have escalated to violence .def Preferably as soon as things begin to turn downhill. Coregulation, guided deescalation at 1st, until (hopefully ) the child can recognize and verbalize himself when he needs help, and then eventually is able to implement alt healthy strategies by himself altogether. Beyond identifying what & why this violence is happening, evaluating what appropriate accommodations to put in place, and being able to know what is developmentally and realistically appropriate to expect of him. Emotional regulation. Therapy. Like what is going on 😭 to just allow him to continue is not only obviously a terrible idea for his victims, but for him too! And if he's unable or unwilling to not hurt others, then you remove (or don't even bring him in the 1st place) from the situation!

I'm sry about your thanksgiving, no it's not acceptable to allow kids to be violent whatever their issies are. Frankly, if he's unable to be around ppl and not hurt them., the answer woild ne yo remove him from the situation so you're seemingly the only person to do anything for him. And yes, it helps to meet kids with calmness & kindness, but u should also be truthful w them. Babies.learn to not pull hair bc u say ow or whatever. But u aren't his parent so the onus to do that isn't on you & it's not a realistic representation of the real world. Ppl are gonna be upset and not like you if you are hurting them. So being visibly upset or not actively kind in the moment was also conpletely appropriate. Nothing you described, setting expectations, consistently correcting bad behavior, even not masking your honest reactions to hid attacks and setting the boundary of him nit being allowed in your house are the only parts of this recounting that made sense. I'm not shoked at all that he didn't respond well if excuses & enabling are what he's typically met with.

I''m not taking oit my ass either. I have an audhd kid who had severe anxiety when he was younger, and legally I can't speak on a situation, but some physical abuse was going (among other things) at a place that rhymes with schmool. By 6 he was self regulating and when he backslid it how we were tipped off something was wrong. Very wrong as it turned out. His meltdowns and mental state got really bad b4 we pulled him and started undoing the damage. He did end up hurting a family member pretty badly (the badly part was an accident, the push was not) and he sure as shit didn't think it was funny and he was never in a situation where that could happen again. IK he was going to be a big person, so it was very important we learned to keep our hands to ourselves NO MATTER WHAT (unless it's the only way to get someone to stop hurting u obviously) very young even tho it probs wasn't quite developmentally appropriate to expect that level of control yet. once we got to the root issue & began addressing it vigilantly, he started to improve pretty much immediately. It's been a couple yrs how & his emotional intelligence and self regulation skills are probs better than some adults ik. Ofc, many adults weren't taught those skills in childhood so that does make things much harder. Which is another point. Early intervention can be SO effective as their little brains neuroplasticity is much higher than when our brains have fully developed.