Hi Kathleen, Would you post the children of your William McKee born around 1785?
In Hardeman Co TN I have:
John McKee married Diana C. Goodwin 20 Sept 1832 at Hardeman Co TN
William McKee married Mary Ann Kerly 21 Jan 1833 at Hardeman Co TN
Have zero other information for the above.
I have my husband's McKee Family in Hardeman Co back thru 1847 with William Thomas (Raiford/Radford, possible additional middle name) McKee, from I don't know where for sure--have online sources which say TN, AL, MS, married a Keziah Sellers from NC Oct 1847 at Hardeman Co TN.
As you commented, you know many families he is not from--perhaps we could exchange information for possible links.