In the 1860 Oregon County census, John Simpson, born Tn. 30 yrs old and Martha Simpson, born Al. 31 yrs old are living in the household of Robert Casey, born Il. 30 years old and Julia Casey, born Il. 30 years old.

David G. Simpson,22, Tn. was living in the household of Valentine Simpson, 70, NC and Lucretia,66, Va

Found none of the above named persons in the 1870 census of Oregon County.

Hope this helps.