He was diagnosed with schizo

My boyfriend’s son is 28 years old. He was diagnosed with schizo typal personality disorder by the army. He is homeless and doesn’t think anything is wrong with him. His father let him live with him for years while he refused to work and did nothing. Finally, he kicked him out last year as it was taking a heavy toll on his father. He constantly comes to his father’s house asking for food, money, etc. His father usually gives into him, but he cannot take care of this 28 year old man who won’t get help or do anything for himself. We really don’t know what to do anymore as he is of age and has to seek help for himself. In the meantime, it is detrimental to my boyfriend’s health and well being. His son does weird things like tries to cast spells with dead snakes and throws them around my boyfriend’s property. I find this behavior very disturbing. He obviously has mental issues, but we can’t do anything to force him to get help. I see this young man as a tragedy in the making. Do you have any ideas or thoughts that could help us? Thank you.