4 siblings with Bipolar looking for advy

My parents had 9 children, 4 have/had Bipolar. One of my brothers completed suicide in 2023 after 40 years of rapid cycling.

My sister manages her Bipolar quite well, she exercises, eats well and manages work.

Another brother has had more psychotic episodes since suffering a traumatic brain injury a few years ago.

The other brother with Bipolar is almost 59. He seems to be getting worse e.g. either low for months, then experiencing mania. He doesn't have a partner, and has burnt a lot of bridges. He has adult children who are scared of him, but love him.

He is currently in a psych ward after punching someone. Police brought him to the psych ward as he is in denial and involuntary. I tried to help him. I was gentle, saying to him you're becoming unwell, go to your GP to get sleeping meds. He told me to mind my own business.

I find it very hard, someone needs to be there for him, but his behaviour makes me want to stay away. Do you think I should keep trying with him?