What should we do about semi-functioning bipolar alcoholic father-in-law?

My father in law is a semi-functioning bipolar alcoholic turning 61 this year, he has been living independently for a few years after my mother in law separated from him due to verbal abuse, manipulation and money problems due to the alcoholism. The immediate family (my partner, his brother, mum and dad) have all been still on good terms for the most part having regular dinners etc.

While he has been living independently he has been in and out of short-term mental health clinics and is medicated for his bipolar (amongst other things) still drinking very heavily and smoking marijuana. He has manic periods where he attempts to make “big deals” (Delusions of grandeur) and when my partner and his brother attempt to talk to him, check he is taking his medication he becomes very verbally abusive and continues to write huge emails in essay format to various family members and heads of psychology clinics making big threats and continuing to verbally abuse and ridicule anyone who tries to get in his way/talk any sense.

All of this was manageable up until Just over a month ago. My father in law had a manic episode and forgotten to take his medication (due to passing out drunk) and was caught walking around the apartment block naked and after ambulance and police were called they found marijuana in his apartment. He was kicked out of the apartment complex but lucky did not get charged for anything, and moved into a temporary mental health clinic until we (my partner, his mum, his brother and I) could weigh up our options and find him another place to stay.

Since then, Coronavirus has happened and he has gotten kicked out of the mental health clinic for sneaking alcohol and drugs in and verbally abusing the head psychologist. He has been living with my partner and his mum and to make matters worse is currently obsessed with trying to sue the landlord of the apartment block he got evicted from (including contacting lawyers etc and getting the family involved). There were rules that he was meant to stick to to keep living at the family home and he broke them but is now back living there again as there was nowhere to go. He needs to applying for the mental health housing commission himself however just isn’t doing it. What do we do? He is still psychologically abusive and draining, can’t be left at home by himself. We don’t know whether to completely shut him out (have tried once and failed- he went to the hospital and self-discharged and slept on the street, constantly texting everyone and guilt tripping) or to try and get some sort of power of attorney to put him in a mental facility? Any suggestions or help is greatly appreciated.