Finding a maternal descendant of a person born in the 1700s is easier said than done. Most of that is due to the name changes and the paternalistic nature of record keeping in the early days.
I began my effort by offering $500 for someone to do the work for me. To quote that blog from May of 2015, "The Abigail DNA Project will award $500 to the person who can identify a living maternal descendant of the mother of Joel's children and convince that person to submit a sample for mtDNA testing."
When it became obvious there were no takers, I dived into it myself, descending the maternal tree of Jemima Campbell, hoping to find a researcher on ancestry.com who might know a living descendant. I hit some dead ends, but in the process I probably did a lot of genealogy that someone will find useful. I finally thought I was close and left a few messages for people managing family trees on ancestry.com. One was a woman who manages a wonderful tree called appropriately "The Karie Sexton Family Tree." I left a note in February of 2016 inquiring about the maternal lines that descended from Emma Mourhess (see tree below). She did not see the "You have a message" icon on ancestry.com until October, but her reply was encouraging. Her husband had a cousin who was a maternal great-granddaughter of Emma Mourhess.
Soon Carol Anne Baker (my long lost 6th cousin) and I were talking. She is the 5th great-granddaughter of Jemima's mother with an unbroken maternal line. She submitted a sample for mtDNA testing and has agreed to share the results with her "cousins." Interestingly, Carol's maternal ancestors of the last six generations, all lived in the general area where Joel spent his last years.
Mother of Jemima Campbell (name traditionally given as Nancy Leonard)
Rebecca Tice (daughter of Jemima Campbell)
Sally/Sarah Crowl (daughter of Rebecca Tice)
Emma Mourhess (daughter of Sally Crowl)
Frances Leona Crane (daughter of Emma Mourhess)
Frances Emma Colburn (daughter of Francis L Crane)
Carol Anne Baker (daughter of Francis E Colburn)
Part IV will discuss the results of the mtDNA test.