15 year old son won't go to school part 2

I posted the other day and received really good advice. Same son, different problem.His sister, former heroin addict is living with us again with her 4 year old son and boyfriend.My son is very unhappy about this and wants me to kick them out. It's my understanding that her boyfriends grandparents are buying them their first home so they are living here short term.They have been here about two months. They were living in apartment for about a year and a half, but they didn't have a lease and they had problems with the landlord. I let them move back in knowing this isn't forever, it's short term and they have been looking at houses.Here is the problem. When they lived with us 3 years ago and they were using, they stole from not just me, but my son too. He had a DS which I replaced and they stole the replacement and all the games. They stole PlayStation games from him too. They took all my good jewelry and my phone, numerous things were taken and pawned for drug money.Whenever something was taken from him I got it back and or replaced it. There were some games he didn't want back so I bought new games that he wanted. I tried to make sense out of a no win situation. I had a baby grandson. I couldn't kick them out when he was so vulnerable.They got clean but never apologized to him. He is angry. I had promised him I wouldn't let them back. But they are clean now.He took money from them in the last few days. $25 and some quarters. And he took a shirt yesterday. I got the shirt back and I'm washing it to give it back. I took $40 out of my checking and gave it back.I made him promise he wouldn't take anything else. His sister has said she will start taking his things. I have to tell her if she retaliates that they will have to leave..I have a crisis management team involved and plan to call the case manager tomorrow. We are going to have family therapy set up in the next couple of weeks but in the meantime it feels like world war three in this house. I work from home and I'm always here and feel every bit of tension. And I have to work like this, it feels like a sinking ship with no lifeboats.Any thoughts or impressions I would greatly appreciate. I got really good advice with the last thread and I hope you can help. Please, don't hold back. Any advise is helpful to me. via /r/Parenting http://ift.tt/2s8hTzW