Have you found the family in 1880 and 1870? If so, have you taken note of what white families were nearby? Although it is possible that they were slaves of a family with the same surname, that is not always the case. But even so, you first need to find the family in the earliest census possible and that would be 1870 if they were slaves. Once you note which white families, probably EATON, were nearby, then that is the family you would need to research. Warren Co. has some good will abstracts available and checking out the slaves in a particular persons will might be helpful once you find out which families are nearby.