Yea thats a messed up situation J.
I think I would crack down on him a bit more though.
You wanna steal? Cool,Ill just help myself to your tv,stereo,cell phone,etc.And I wouldnt give it back until his behavior gets back in line,particularly concerning the school work.Oh and that job?..Ill be speaking to your boss and until further notice Ill be standing with you in the bank and smile when you hand your paycheck to me.
Aggression? Theres a way to treat that too.Put him doing some hard work in the yard while you stand over him and nit-pick him while hes going about it.Work it out of him,and give him no compensation for doing so.
Now concerning the disabled daughter whos picked on..there I would have a real problem.Any time I see that I would make it a point to get sideways with him for a bit to see how he likes it.I wouldnt have that one bit at all.
Social life..can I get a LOL? Not until things iron out.
And since he likes to hide his ill-gotten gains around his room..
Remove the door to his room.Remove all objects that can be used to hide things,possibly even padlocking his closet.Have him keep the room absolutely pristine,and if he doesnt theres always more work to be done,including cleaning his siblings rooms.
Some may say this sounds mean,but what you have on your hands is a bigger problem waiting in the wings if you cant break him now.Extremely strong-willed individuals often require stronger than necessary punishment when they refuse to get back in line with right/wrong behavior.Not everyone would agree to this kind of approach,but when rationale and reasonable punishment fail,steps must be taken.Its either you now or prison later.
I wish the best for you though J..I know that no matter which way this falls it will be a hard road to travel.Hopefully he is just going through a phase..I went through one of these myself.
I was a good kid until high school.At that point I just literally lost my mind.Stealing,vandalism,fighting,arson,minor drug use and other unsavory characteristics were what my mother had to deal with.Thankfully, my mother was a hard woman.The majority of the things I did she never knew about,but the things she did catch me doing she gave me sheer hell for.At times I hated her back then,but later on..prob early/mid 20s..I know why she did.When it all fell in place and even now Im so glad she was.It literally saved my life.