A Sarah Marley is in the 1870 census with Archibald Marley in Clay, MO, next to Ray Co. Archibald is believed by many to be an ancestor in my Marley family. This Sarah Marley was from Kentucky and two sons are listed, both from Kentucky.Did your GGGGM have sons as well as daughters born in Kentucky?
In Clay Co. records on Ancestry.com, an UNKNOWN Marley, first name not listed, married a Mrs. Sarah "Horton" on Oct. 2, 1856, in Clay Co. just 8 days before Jane Marley, Archibald's dau., married John Hightower at the same place, on Oct. 10, 1856. Your ancestor Nancy Hooten married on Oct. 12, 1856. Perhaps it's just coincidence that these marriages occurred all at once.
Does the letter throw any light on these subjects?