I received, out of the blue, an email from Danny Hall, a genealogist based in Salt Lake City, that questioned the first generation in my family tree, Halls From Devon to North America. The reasoning and evidence he presented makes a compelling case as to why the current root individuals Thomas Halls and Margaret Tawton, should be replaced with John Halls and Mary Nelson. The change is both major and minor. Minor due to the fact that it is easy enough to adjust a tree when the first two individuals are being changed, major because it means a number of people who were not previously in the my tree will be added and tracked.
There is also the possibility that John and Thomas Halls were brothers. They both lived in Meeth, and they married within two years of each other. What I need now is to get more parish registers over a longer date range, and apprentice registers wouldn't hurt either to both solidify the relationships and find more relations.
I have not made the changes yet, but I expect that I will make them in the next few weeks once things have settled.