I have not been able to identify any relatives of my 3rd-great-grandmother Mary Nevins, other than her husband and children. I know that she was born in Ireland in the 1830s and was in the Davidson County, Tennessee by January 1855, when she married my 3rd-great-grandfather William Dow Gatlin.
I don't know whether she immigrated to the United States with other family members. I searched for others in the Nashville area with the surname Nevins, and found Robert F. Nevins, a grocer. He turned out to have been born in Tennessee about 1830. He couldn't have been Mary's brother.
I found a death certificate for Alexander Nevins, son of Joseph Nevins and Mary Haley born 21 December 1832 in Ireland. He died in Nashville on 8 April 1922 at the Little Sisters of the Poor home. However, he had previously been in the National Soldiers Home in Washington County, Tennessee. He had previously lived in North Carolina. He had initially enlisted in the U.S. Navy in 1857 in Boston Massachusetts. I have not found any evidence that he and Mary were related.
The names of Mary's sons may provide clues. My 2nd-great-grandfather was named John William Morton Gatlin (but was usually known just as William Morton Gatlin or William M. Gatlin.) His paternal grandfather was John McNairy Gatlin. His father was William Dow Gatlin and his great-grandfather (his paternal grandmother's father) was William Gower. Perhaps the name Morton came from Mary's side of the family. Another son was named Clarence Bateman Gatlin. I do not know of anyone (family, friends, or famous people) that he could have been named after. These names also may have come from Mary's side of the family.
Mary died on 9 September 1888. Her death was recorded in the Davidson County, Tennessee death register, but parents' names were not recorded then. Researching Mary has definitely been a challenge. Hopefully I will eventually break down this brick wall.