Wrong William or Sloppy Genealogy

In the previous post, I mentioned looking into the possibility that this William was one of my ancestors. He is now claimed as an ancestor by an unrelated McCown line in many different family trees of various surnames. Claiming is one thing, but proving is the color of another horse. The rest of the non-related line of McCowns had relocated to the American colonies by 1740,some in PA and some in VA. There are brothers shown is some family trees not shown in others who are known to be related by DNA. Why would this William alone move from Antrim to Fermanagh while the rest of the family moved from Antrim to the Ameriacan Colonies? On the surface, it looks as if it is all grasping at straws. The nearest name in Fermanagh for the location of this William's death is Knockmakegan, not Knockmaoleigan. So far, the closest match for McCown in knockmakegan is McCue,not McCown so to get to the truth of the matter some on serious research will have to be done, probably in Ulster.