I know you'll be interested that during my visit to the William L Clements Library in Ann Arbor where I viewed the Grimke family papers I came across correspondence between Hester Snowden, a slave, in Charleston and Sarah Grimke. Sarah explains that she would give Bible lessons to the Grimke house slaves and those of neighbouring households in Charleston, and Hester was one such slave. I now discover that Hester was John's Snowden's mother from this Freedman's Bank Record.