Sorry, but if someone asks for help I will help them to the best of my knowledge. I will tell them it is limited. If you want more then that you really are wasting time. You can tell someone not to teach it, but you really don't know if they listen unless you follow them around. I can send you links with the legal definition of selfdefence all its limitations, even what I have looked up for handicap people. It doesn't make me an expert, but it does mean I'm not blind to it. It would depend on the person as to how you would teach them. If someone has a mental handicap it would be much different from someone who does not. It doesn't matter how old the person is, it depends on their own understanding as to what they can learn.
You may have mentioned it, but how much training do you have again? IMHO, what you're doing, is equivilant to a white or yellow belt teaching someone. Again, while your heart may be in the right place, if you yourself dont have a solid understanding of things, how is the person you're teaching going to? In all of the schools I've been a part of, nobody even thinks about teaching, until you're at least brown, maybe green.