i think you've "DONE" more than enough to this man and to his parents. and in very short order. i don't think you can really see the chaos that YOU have caused here.....
you "forced" a home detox on him that almost killed him in week one
you took him to the ICU by date #3
you invited him to stay with you , he had a seizure, off to the ER and you signed Emergency Power of Attorney
you brought him back to your home - he got drunk again - he left got a DUI
you then did a Marchman Act and he was sent to a mental institution
and that was just the month of JANUARY
February, AWAY from you, he stayed sober and began to feel better and have a better outlook
March he came to stay with you and in four days was again blind ass drunk and you stuffed him in a cab and sent him on his way.
and now are panicked about his whereabouts and getting his parents all worried and concerned. and you are considering filling a missing person's report and wondering what to do if he shows up during an active search.
you must thrive on drama. but seriously, look at your own actions here and what you have helped bring about in less than three months time.