Unruly 7 year old

Hi everyone. Ive no idea if this is the right sub for this but lets give it a go.TLDR; I’m a caregiver for my autistic nephew but the brother (same age) is so bad its affecting my motivation to keep doing my job. Talking to parents hasnt helped. What can i do?This might be a bit long so bear with me, this is about my 7 year old nephew. Backstory: my older sister got remarried to a man who is much older than her and both already had children from their previous marriages his son is now 16 her daughter is now 12. Shortly after they got together she gets pregnant and has his baby. After a couple of years she finds out that right before she got pregnant that he had gotten another woman pregnant a couple months prior (pretty sure the BM reached out to my sister and the kid looks just like my brother in law). BM is bat shit crazy and abused the kid so fast forward about 4 years and my sister and her husband have to take the kid into custody. Heres where my question starts, the “new” son has very low functioning autism (which i truly believe if he had the right care sooner he would at least be verbal) and has taken up a TON of the attention with therapists dr appts etc etc. Keep in mind both of the little boys now are the same age with just a couple months between them. I’m very involved because i am now a caregiver for the autistic one BUT the other boy is SO bad. My whole family has tried to bring it up to the parents about how bad he is (wont listen throws screaming fits is disastrous) and my sister gets VERY defensive over him. The husband cant even do anything about it because she gets so mad. I caught the boy flipping me off once and he throws his electronics and breaks things when hes mad. And the main reason for this behavior (i believe) is that he was introduced to electronics and such at too young of an age. I also understand jealousy plays a main part in this too but this behavior has been going on and only getting worse for the last few years. Its so bad that the autistic boy is starting to pick up and learn from him and it makes things way harder on me. I’m scared about how the unruly boy is going to grow up but have no idea how to approach the situation or if i even should. This post doesnt even help describe how bad he is but i’m trying to keep it as short as i can.Does anyone have any advice as to what i could do when the parents arent around? Ive tried being very nice to him and have also tried reprimanding him (by taking away his switch or tablet etc never spank cus thats not my place) and that just makes things soooo much worse. I really enjoy being a caregiver but i cant keep doing it if the unruly kid wont change. ANY advice is welcomed. via /r/Parenting https://ift.tt/368kzB3