That's interesting, all of these "Down by the waters rolling" variants are very similar to each other.
There doesn't seem to be a sound recording of Mrs. Griffin's "Two Sisters" on the floridamemory site, even though many other of Griffin's excellent ballads are available there.

I also remember a recording of Ellen Stekert singing a New York version that also had the harp in it:
Songs of a New York Lumberjack