Thomas Blackwell Dunnam was son of Jacob Dunnam and Elizabeth Blackwell.I have Jacob Dunnam b. abt 1750 in Georgetown Dist,Prince George Prov., SC., d.abt 1798 in SC. Elizabeth also b. in Georgetown Dist, SC. Two children shown on my family group sheet are Thomas Blackwell Dunnam,b. 23 Oct 1781, and Julia Dunnam who married a Bailey.
Family Treemaker has several Dunnam family trees you might be intresred in.