There is a genealogical division of Middleton Gardens Plantation in Charleston, SC. I have corresponded with them over the years...they do not know Edward Middleton's wife's maiden name either.I spent a lot of time several years ago to no avail...
I am a descendant of Major Gen. Robert Howe b. ca 1732/joined DAR on him. Also have proof of my lineage to Gov. James Moore and his wife, Margaret Berringer of Barbados.
Those were easy to confirm...Sarah Fowell Middleton How/Howe has been an empty chase...so far.
If I am fortunate enough to discover her maiden name, I will certainly remember you.