He's let people know. This means he's probably got it on paper also that if something was to happen to him, he believes that it would be you that is responsible. I have a little experience with this.
My ex is a high priced escort. One of her now ex clients is a producer of a popular tv show on mtv. He went to seeing her once a month to several times per month. The dumb fuck though he was so wonderful that he had himself a girlfriend all of a sudden and stopped paying. She had been playing the part he wanted. Telling him how wonderful he was and that she loved him....like a hooker is supposed to to keep the fantasy going for this lame.
When he stopped paying, she lined up another one of her exs' that is a bodyguard back on the east coast. She documented that this person owed her money and that if anything was to happen to her she felt he was responsible. She made out an invoice and she, along with the bodyguard delivered it in person to his office. The invoice was for just about $25k(funny, huh?) He paid. I would have been happy to go her....as I do these things for her now....but I happened to be incarcerated at the time.
I suppose u just have to try to work out some kind of payment schedule with him brother.