This may be a long process but go to the slave records and tax list and list each time you see the white family surname up to 1886. For the person in the family you know if it tells what state he was bn and the state his parents were bn compare that with the names from 1820 to 1880. They maybe connected. Then look thru the slave census in 1870 an see who is next door, down the street, around the corner from the family member. Also compare names from the federal census for the community in question. Especially places of birth. Some families with different surnames had relatives living in households. Chart all this out by each year and compare info. I stumbled on to family members by this method. I hope this helps.