+1,
Its a difficult one, you ring the police which is probably the right thing to do in an attempt to get the idiot banned before he kills someone for driving whilst on drugs, just as bad in not worse that drinking & driving in my opinion. If I knew he was smoking it then the Police would have been involved, however, he could have smelt of weed because his 2 cronies were the ones smoking it. The odour would have been on his clothes, but it does not mean he was using weed.
However doing the above won't get your car fixed without going through his or even worse your insurance if he is not insured.
Be careful though. You have gone for the way I would have. But the family maybe attempting to delay the situation and have not intentions of paying you out.