Original: After appearing in facsimile in an article written by John Nicolay in 1894, the Nicolay Copy was presumably among the papers passed to Hay by Nicolay's daughter Helen upon Nicolay's death in 1901.
Simplified: The Nicolay Copy appeared as a copy in an article written by Nicolay in 1894. After that, it was thought to be among the papers passed to Hay by Nicolay's daughter Helen when Nicolay died in 1901.