Your info has possibilities.The only known factors are that a Mary E. Nicely was our grandfathers mother and at about age 7-8 he went to live with the Cliftons. When he became of age he asked "what last name should I use?" and was told "whichever name you want." We understand that he was more 'beholden' to the Clifton family, so he chose that one.
We have Mary E. Nicely listed in the 1870 census as 22yrs, born in VA. This entry lists children as Wm. 3, and James M. as 7 yrs. Something else interesting in this entry is also a listing of a Mary E. Wells, same age as Mary E. Nicely, born in VA. There is no father or man of the house listed.
That is about all we know. Mary E. Nicely comes to a dead end after 1870.