About Nellie Ketchum Earp (Bartlett)
"The Earp Family Genealogy" lists Nellie as Nellie Bartlett; in "I Married Wyatt Earp," p. 57 (Note 6 -- Notes to Chapter 3) it gives her name as Nellie Bartlett Ketchum and says that they (James Earp and Nellie Bartlett) were married April 18, 1873, in Illinois. However, no sources are cited for this information.
The 1880 Arizona census for Tombstone shows James C. Earp's wife as "Bessie" and Hattie B. Catchin as his stepdaughter. Alvira "Allie" (Sullivan) Earp (wife of Virgil Walter Earp) refers to her brother-in-law as "Jim" and his wife "Bessie" throughout "The Earp Brothers of Tombstone: The Story of Mrs. Virgil Earp," by Frank Waters.
It appears that Nellie Bartlett and Bessie Earp are the same person. Possibly she was married before to a man named Ketchum or Catchin, or that was the name of the father of her daughter, Hattie.