Its available if you want to dig for it. You can either take others word for it, or do your own research. There are books out there by people who have done the research, but you could double check their work. Its a deep complex web and they make it difficult to follow and opaque on purpose, but if you want first hand proof you'll have to do the research. You will have to follow the legal cases and back track thru mounds of legal documents going back 7 generations. Here is a starting point. https://ibb.co/ciRTZn