Oaklawn Cemetery in Algonac has 12 "Hill" family members listed. Edward Warren (1855-1941) s/o William Hill and Ellen Shipman; Fannie 1868 - 1948 d/o Frederick Parker and Ann Wells; none of the others are indicated as their children. However, William Hill (1786-1875) s/o Jacob Hill and Dorothy Seck is also buried there. William's first wife was Elizabeth Robinson.
There is also a William (1831-1911) who is listed as the son of William Hill and Sarah Andrews who married Ellen Shipman.
I'll be glad to forward more information if any of this seems to connect.