According to one of my reference books Sarah Ogan Gunning was the sister of Jim Garland and half-sister to Aunt Molly Jackson. She was the daughter of miner, Baptist minister and labour organiser Oliver Perry Garland and married Andrew Ogan when she was 15. After Andrew died (in 1938)she married Joseph Gunning in 1941.

As far as I can tell Florence Reece was not related.

There is also some information about them online at Appalachian Protest Songwriters

Some protest songs from the mines can be found at Songs From The Mines

Mick