She was living next to William Johnson in Brandon in 1860, as a servant in the home of Stephen and Roxy Martin, who figure in one of the land transfers that Janet Decker informed me of.

She is the daughter of Henry S. and Lucretia Johnson. The family (listed as H.S. Johnson, same as in 1850), shows up in Harrietstown, Franklin County, in 1860, and Joanna is double-counted there and in Brandon. Seems likely there’s a connection between Henry S. Johnson and William. Henry lived near to a William Martin, who may have been connected to Stephen Martin, at whose home Joanna was a servant.