Will lists Rebekka J. WIllson and Bettie Rhodes as Sarah J. Johnson's sisters.
in the North Carolina, U.S., Wills and Probate Records, 1665-1998
in the North Carolina, U.S., Deaths, 1906-1930
Have you seen this document - http://www.ncgenweb.us/bladen/vrecords_dir/books/johnsonfamilyhistory.pdf?
I didn't see your family and I am sure that is has all of the faults that these types of things tend to have, but someone made a real effort to outline the Johnson family in that area.