Hi Richard, I'm not related, but I was bored tonight and looking for something to do.
According to the IL Sec of State's online marriage index, Frances and Manuel Reed were married in Saline County, IL on Sept 18 1856. Saline County borders Hamilton County: http://www.ilsos.gov/isavital/marriageSearch.dohttp://www.ilsos.gov/isavital/marriageSearch.do
I suggest you look at the 1850 Census for Saline County, IL at the family of William Johnson.
William Johnson age 55 born Kentucky Elizabeth age 47 born IL Green age 21 Caroline age 18 Bluford age 16 William age 14 Fanny age 13 Richard age 10 Thomas age 8 Saphronia age 5 all children born in IL
If William and Elizabeth Johnson named their daughter Frances for her maternal grandmother then they probably called her Fanny, even if she no longer used that nickname after she married.Just a thought.