Could you try to re-home them? Like there are chickens rescues some places. I have no clue if there is one by you or if its an option, its just an idea. On second thought, if they are suffering too badly, the right thing to do would be to cull them. I don't know a whole ton about this topic, and just spit out a random idea. Please do not take this as hurtful, I don't mean it in that way. I think its so amazing that you care and want to do the right thing! I've seen some bad situations people don't treat or care for, you are certainly doing the right thing.