Not to be a thread killer. Not to take anything from Mr. Li's brilliant research on the subject.
But a lot (not all) (maybe unknowable) of the founder's teaching ability and who taught what to whom, and also who went to who for what, including lineages up and down the time lines of aikido and daito ryu is laid out in Ellis's Amdur's book , "Hidden in Plain Sight". Having just finished reading it in what maybe the first of many times( yes my head is still throbbing), it is illuminating a little bit about this very subject.
Not taking away anything - HIPS is the gold standard.
Ellis was nice enough to include me in the acknowledgements - but I don't think that I really contributed very much.