Robert Todd is probably the second tithe in the tax list entry for Thomas Todd, his elder brother in 1820, then to have gone to Carter County TN by 1829, returning to Washington Co 1833-1838, then moving to Dekalb County Alabama by 1840 and then Johnson Co Missouri by 1860.
https://sites.rootsweb.com/~mcmurtriecfr/richard/todd/tf55.htm