Are there any young person homeless charities where you live. I had to "report" a street sleeper one freezing winters night on the way home from work. I checked the internet and found a group of young people who are experienced in going out to rough sleepers and checking that they are safe, telling them their rights etc.
I'm not in US so the name of that charity won't help you - but it seemed good to get experienced young people helping other young people: they know the stories, the evasions and the limits of safety.
I don't know how people deal with this in their own family because it's hard enough to encounter strangers using mixtures of behaviours - reaching for help, manipulation, putting themselves at risk. It's a huge challenge.