yes - Joyce did the hard work - I think she (maybe John Robinson as well ?) started with the tree in the manuscript of A W Moore's Old Manx Families which had a Royal descent but found that Moore had confused the various Taubmans - I too was also confused as no Arbory records exist for much of the period so I worked back under my own steam to arrive at the same conclusion - I found various bits of confirmation in Land records and should be able to add more after a bit of research in Museum.
I continue to receive various emails from the person who started this hare running - the most recent has "Fortunately, your antiquated methods of collecting genealogy information, being as error riddled, faulty, and completely subjective, as any that I have ever seen, leave me with a mere bemusement.....I cannot control the minds of the small and feeble."

There is a website www.thePeerage.com which is a mixture of accurate trees derived from reputable sources to those based on somewhat strange genealogy as for example my initial query about a child born to a woman dead at least 15 years before birth (that tree is still on the referenced site) like much of web material (eg the patron submitted IGI entries & even wikipedia) you cannot immediately tell the sheep from the goats.