Possible, but no records exist. (Common frontier problem). Jeremiah Adkins was later married to a Duncan girl (possibly Juanna's cousin?). Complicated relationships existed with many cousin marriages existing in the Duncan Clan. (Small community with possible religious restrictions on marriages.) The Scottish Clan structures persisted for centuries after the great migration.
No so far, testing has not yet taken place on that line. (It is possible that Jeremiah's younger brother was the father but testing would not distinguish between them). ........................... My father's 1st cousin Dave Duncan tested (a J1 y-haplogroup) but belongs to another paternal line. ( Apparent Paternal lineage is Welsh? Jones Family).
JW (Jasper) Smith, wrote in 1924 articles to Anderson County Newspaper he stated, "As I said in the other issue the widow Duncan built a cabin near a spring, where allen Phillips now owns." In Aug. in 1925 he wrote, "While he (his Grandfather, Moses Duncan) lived up there (near Cherokee, NC) his brother-in-law died and he came to Tennessee and brought his sister." This is written documentation that Juanna was a widow & had been married in NC. So it is family history that she was married. These people grew up hard & fast. I wouldn't think that the children were smoothed over with tales of a marriage to hide illegitimacy.
Juanna was named in a Bastardy Bond signed by her father and oldest brother. Embarrassed my Grandmother so much ,when she found out, that she stopped researching her Duncan Genealogy. There was another younger Juanna Duncan who was married, I was confused by her records and merged them until I realized my mistake.