Margaret Blackstone married Joseph Harry Barnum
She was the daughter of Thomas Blackstone , born 1833, in Georgia, died in battle April 1862, Williamsburg VA. (He may be John Thomas) She was born 1858, died 1921 in Oconee County. Her son, James Thomas Barnum born 1882 . ( one of Frank's boys lived with him. Margaret's brother Benjamin , born about 1857, had a son John F. (Frank) born about 1882.
I don't know if Margaret had another christian name . The only Margaret Blackstone I can find in the census is 1880, mother Dicy.
For certain, Margaret Blackstone & Joseph Barnum per death certs her kids. And definitely 1900 census for Ben' s son ,John F