I don't know how much you have, but I looked for your people on the census.
1880 james 39 and rosa 32 with francis j,12 in alligator township chesterfield sc there is a hugh and margaret living down the street
1870 couldnt find james but hugh and margaret were there there was a f. poston 24 living with a e poston
1860 lynchcreek marion co, sc there are nine poston families:one is jr and elizibeth with james listed -14 there is a samuel 55 listed with an "e" 58 must be james brother-too young for father francis jane poston dec 1868 chesterfield sc, 11 apr 1930 wayne co, gamarried james roland rogers s/o james wesley dozier and hulda rebecca alexander None of the sc people are in my line. do you know all this?