Sarah Dever was sister of Michael Thomas Dever, who was married to Elizabeth Harrelson. Michael T. was the son of William Miles Dever,son of Thomas Devers and Susannah Jones. William T's sons with Elizabeth Harrelson were Michael Jones Devers (1841) and Ezekial Devers (1845). Those are the teens living at the Harrelson ranch in the 1860 census.
Michael "P." Deavers in the 1850 census at Cane Creek, Il is Michael Thomas Devers.
William M "Dover" in the 1830 census in Gallatin County is William Miles Dever, Sr. born 1794 in Hardin County, Ky, and married to Lettice Wisehart. They married 8 March 1819. The same William M. Devers is also listed in the 1840 census in Gallatin, Il. The William M. (Miles) Devers listed in the 1900 census in New Haven, Gallatin is Michael Thomas Devers' son with Elizabeth Abbott at Cane Creek in 1848.
The William Deaver listed in the 1850 census (age 42) in Gallatin, Ky, is related to Michael T. (age 30 in 1850), but I'm not sure how.
Sylvanus' father was Ezekial Harrelson. His son with Sarah Ann Deavers is William Miles Harrelson, born 19 Feb 1841 in Gallatin county, Il.