Yes, Lynn. Elsie Johnson Ayres wrote two books in the 1970s that are quite large (1000 pages) containing whatever she could find about the families that lived in Highland County, Ohio - Hills of Highland is one, and Highland County Pioneer Sketches and Genealogies is the other. Her information is not perfectly reliable - Ayres has some errors in her writeup of my wife's Bishir family, for example, but it's better than no information in many cases and can help indicate a direction to go with research.

It's probably worth finding all Davidsons in Highland County in the early censuses (1850 and earlier) and matching them against the ones Ayres lists and see who is left over. We did that with several of my wife's surnames and it was quite helpful in figuring out how the various family units fit together.

Have you tested any Davidson males for Y-DNA yet? We've been doing that and it does help in identifying groups with the same surname who are proven to not be related to one another.

I will scan some of the Davidson pages and put up a link here.

Don