Your William was my Great Grandfather and Mary Elizabeth Harris was my Great Grandmother. After Mary died Oct 1850 William married a third time in Sangamon County IL to Rebecca Johnston. William is buried at South Fork Church of Christ, Breckenridge, IL. I have not been able to establish a marriage date to Mary Elizabeth Harris or even a name for his first wife. However, My mother told me he was married prior to Elizabeth and had a son named John who never married.