If the other chickens stay at your place, they become yours. Your feed, your eggs. It seems the people are not into the farm thing. Losing eggs may get them to really think about their priorities.Thank you @BrooksHatlen and @3KillerBs for the advice. I'd first like to try and reason with them tactfully--I do believe if they truly know their hens are starving they wouldn't want that (they just are skeptical of my advice, like they were about ventilation lol). I think they believe chickens are tougher than they are--and they ARE tough, but they do need basics. When I went to close up my run I had to carry some of their chickens out, and some have really prominent keel bonesI'm wondering if worms are also a problem.
I have been giving them some feed to supplement but we've been running through it like crazy now--they REALLY EAT. I also always leave water out. I'm not sure how my husband would feel about feeding them regularly because we may end up with all 12 of them and the turkeys down here on our much smaller property, but that's something I've been quietly thinking about. Let me know if you have any ideas on tactful breaching of the topic.
Thanks again for responding!