Col
I suspect we are into ancestry mythology here - there is a Nov 1703 burial of a Wm Waterson in Ballaugh where the Watterson name was unknown in burial between 1704 and 1835, for which there are no wills (nor land records) and is just 1 of 4 burials noted between 1611 and 1704 - this has all the hallmarks of name spotting in the IGI resulting in rather mixed up genealogy