One way you can tell is if you find a marriage record in the Cohabitation Records created after the end of the Civil War. Former slaves were requested to register their slave marriages with the County between 1865 - 1867, to have their marriages recognized by the State. Barnetta McGhee White wrote a wonderful book, "Somebody Knows My Name, Marriages of Freed People in North Carolina" a three-volume set with those marriages listed. I checked it and found an ISAAC ALLEN - married - MATILDA DAVIS in 1855 in Warren County,NC. I have no idea if this may be one of yours since you don't list any ages in your message, but I would suggest that you also look into Warren County, NC records for your families. Many people who lived in either county had transactions in each of the counties because they are so near, and some of the towns were even intermingled, such as Littleton. Also, many of the people lived on the borders of these counties, and I have found transactions and even census records for some of these people in both counties. I think there was a lot of moving back and forth between the two, and many landowners owned property in both locations.