I would be really cautious about using an unpredictable horse like Chinga as a lesson horse in the first place; correct me if I'm wrong, but you've been hurt by him several times now? Why would you even consider using him as a horse to teach others how to ride? Granted, YOU know how to handle him, but what if he starts bucking while on the longe line, or bolts, or has a 'naughty moment' with someone on him? Then what?
No offense, but you need to think about getting a better trained horse in order to give lessons to other people, or stop giving them all together.
Do you have insurance to cover anyone that gets hurt riding YOUR horse? If not, then you shouldn't be giving lessons either...you need to talk to your parents about getting some form of insurance that will cover your butt if your boy hurts someone, be it from a fall from him, or him hurting them on the ground, or in the paddock.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."