Hi,
Yes John had a brother Job who married Mary Cowley on 9 Sep 1832 in Cold Ashby, she died Sep 1884 and was buried on 28 Sep 1884 in Cold Ashby, they had 3 children, Elizabeth, Joseph and William. I'm afraid I don't know if Mary and Keturah were sisters or who their parents were, my family are the Baldersons.
Sandy