I think I've finally gotten the Barbara Halfhills straightened out.
Barbara Halfhill married William Darst, March 22, 1845.
Barbara Halfhill married Ransom H. Rupe, March 16, 1846.
The Barbara Halfhill who married William Darst is the daughter of Samuel Halfhill and Anna Lemley. William and Barbara moved to Madison, Jay, Indiana. There children are: Joseph (named for William's father), Samuel (named for Barbara's father), and Margaret A. (Other children of Samuel Halfhill and Anna Lemley also moved to Jay, Indiana.)
The Barbara Halfhill who married Ransom Henry Rupe is the daughter of Dewalt and Catherine Halfhill. In the 1850 Cheshire Twp., Gallia County, OH census, Barbara(32) and Mary J.(2) are living with Barbara's brother, Reuben Halfhill. They are incorrectly listed as Halfhill's. Ransom does not appear in the 1850 census records. I believe Mary J. is named for Barbara's sister, Mary, who was my great-great grandmother.
If anyone has any further information, please contact me.