I understand that Mary is actually Mary Polly Elsea (Elsey) who was the daughter of Thomas Elsea (Elsey) who is from Wythe County, Virginia.There is information on the web that may answer some of your questions.See below from a geneaology webpage, Source: http://www.geocities.com/Heartland/Village/2121/TElsea1757.htmlhttp://www.geocities.com/Heartland/Village/2121/TElsea1757.html
James Arterburn b 1771 [VA] d 1867 [Sullivan Co., TN] m (Jan.08, 1798) Mary Polly Elsea b 1777 [VA]
Also, the 1860 US Census has: Name: James Arterburn Age in 1860: 87 Birth Year: abt 1773 Birthplace: Virginia Home in 1860: District 15, Sullivan, Tennessee Gender: Male Post Office: Gotts Crossroads
Moreover, the Shenandoah County Marriages to 1800 has: Spouse 1: Arterburn, James Spouse 2: Elsea, Polly Marriage Date: 08 Jan 1798 Marriage Location: Virginia Shenandoah County
I believe that all of the Elsea's (Elsey's) in Sullivan County are related.Especially the people you identified.I'm from the Isaac Elsey that you listed in your email...