Parenting advise DESPERATELY NEEDED

Okay so this might be long so please bare with me.

Backstory: I have two brothers, 16 and 12. 4 years ago (I had been moved out for about 3 years) my dad got into some legal trouble and was sent to prison for 7 years. My mother basically lost it and after fighting her battle with opioide addiction, she turned to heroin. I then stepped in to help take care of my brothers and dished out $16k to send her to rehab.

About 3 weeks in my grandparents called and said they wanted to take the boys in and wanted me to focus on my growing family (i was 6 months pregnant with my first at the time)

They called DSS and my mother was given 90 days to hold a steady job, have a home with the boys having their own room, and be clean. But to our surprise, she never even tried. In fact she hasnt spoken to any of us since she returned from rehab. She packed up and moved to her home state.

Then we found out my brother (12 at the time now 16) had been smoking pot and helping my mother sell pills. And since then this has been an ongoing issue. He will get cigarettes, vapes, and pot and hide them through the house. Hes been in counciling because, well, this has been tramatic for all of us and no child deserves any of this.

He does GREAT in school. He's an honor roll kid and perfect attendance, he does great in any sport. But he chooses the wrong crowd and thinks he's slick Rick. His forst job he got fired from because he stole the store Ipad. He also was suspended from school over stealing a bag of chips and they wanted to press charges (that was a little over the top if you ask me)

Now my grandparents have had enough of him lying and acting out. So over the summer they sent the boys to live with another couple who have known them through all of this. New school, new home, new friends. A fresh start. He was given a car to drive back and forth to work and school.

So earlier this week my grandpa calls to tell me he has been coming in super late from work. Like 1:30 in the morning. Hes a bust boy at Olive Garden. They close at 10 on weeknights.

One excuse was he talked to pur dad and sat in the driveway for hours trying to think of something he could do for him. (Debunked because i talked to my father and he said he doesnt call him after 8)

Another was that their was on old lady outside one night and he took her to eat. It's possible but i dont think my brother would just load someone he doesnt know into his car.

Well, tonight, he told my grandpa he was at work when he was 45 minutes away. When he arrived home he was "so high he was slurring his words" now ive smoked alot of weed. Ive gotten VERY high and i have never slurred my words. So im concerned it might be something more.

Over many incidents, hes been taken to the police station, hes been talked to by all of us, in counciling, grounded, no activities, and yet he always finds a way to get back into trouble.

If this were your child, what would you do? My grandparents keep asking me and i dont know. Im concerned but we cant just put him a padlocked room. They are old. Almost 80 and cant do this. And the last thing i want is my 12 year old brother to do these same things. So please, give me advice to give them.

Also, if you made it through all of this. Thank you. I know its a lot.