It would appear from census records that you are incorrect on where these 2 people were born. In the 1920 census in Columbia County Page 163 is John W. Blake age 43 born Arkansas, father born South Carolina, mother born Arkansas. Children in household are John W. age 8 born Arkansas, Jemima age 6 born Arkansas, Pauline age 3 born Arkansas and Martel age 1 born Arkansas. In 1910 census Nevada County is John W. Blake age 33 single father born South Carolina mother born Arkansas. In 1900 Census Nevada County Page 208 you will find a Ellen M. Hendricks age 47 born Arkansas with a son Fletcher age 17, daughter Nora Blak age25 born Arkansas and son John Blak age 23 born Arkansas. In 1880 Census in NEVADA cOUNTY is Ellen Blak age 27 born Arkansas with son Junious age 6 born Arkansas, daughter Nora age 5 born Arkansas, son John age 3 born Arkansas and a Charles Blake age 21 listed relationship to Ellen is shown as Brother born South Carolina. Ellen's father shown born Alabama, mother born Arkansas. Ellen's last name is listed on census as BLAK no E. Charles' last name is listed as BLAKE. Either Charles is her brother in law or she was a Blake who married another Blake. In 1870 census Columbia County is one John W. Blake age 53 born South Carolina with wife Harriett age 47 born South Carolina and in his family is a son Charles age 12. There are 3 other sons in family, Green age 19, John age 17 and Theodore age 14. BY looking at the 1880 census records for Green, and Theodore it is clear that the only other son John has to be the father of your John and had died by the 1880 census.