Yes, I have the second wife of Col. John Blair McLin listed as Mrs. Margaret Naff on page 64 of my McLin Memories book: "JOHN BLAIR MCLIN (Col.), b. 07 Feb. 1820 in Little Limestone, TN. d. 05 May 1877 m. CATHERINE JANE EARNEST on 05 Dec, 1850. Catherine died tragically on 17 Jan, 1855, only three months after her infant daughter’s death. Col. McLin later married Mrs. MARGARET NAFF, widow of the Rev. JOHN E. NAFF, and no children were born of the second marriage."
The rest of the entry goes on to expand on the Col., but there are no more mentions of Mrs. Naff.
My main source of information about Col. J. B. McLin is firstname.lastname@example.org.