Several males from this line or lines very closely associated with it have participated in the Alexander DNA project. A few with close DNA matches do not descend from James, and this may provide clues.
About ten people have provided lineages, and, either late today or tomorrow, I will post additional family information, after I get it worked over.
Roger Alexander, who posts here and is coordinator of the DNA project, may have more information. Neither he nor I are part of this family.