Jerry, I was wondering if you had been given some mis-information about the ancestor of John McKnitt Alexander? Or maybe you are referring to a completely different line??
I have been studying this family for some years now and we do believe that our "original 7 brothers" were most probably descended from William who is found in Raphoe Hearth Tax rolls in 1665. This William---although not confirmed is believed to be the son of John of Eredy who was found in Donegal County, Ireland in 1613 land deeds as tenant of James Cunningham Esquire. DNA has told us that our line is NOT descended from the MacAlisters of Tarbert or Stirling Alexanders who are haplotype Ria. We are Rib---so not related. So either the connection of John of Eredy is incorrect, or John or Eredy's connection to the MacAlisters of Tarbert is incorrect.I am inclined to believe that John of Eredy came from Ayrshire where his landlord originated.
Some early material had us descended from Rev. James Alexander of Raphoe, but this has been found incorrect. Even earlier material had John of Eredy descended from Rev. James Alexander and wife Mary Maxwell. They did exist, but their son John did not come to Ireland. I can send you details on that if wanted.