according to my grandmother, Elizabeth L. Ogg, Martha Susan Todd, (her grandmother) had the following brothers and sisters..her father Caleb Todd, had three wives i think, they would die and he would remarry, and have more kids..this could be why you don't have a complete list of his children.
Isaac Todd, brother ;married Betty Almond. Margaret Todd, sister; never married. Georgia Todd, sister; married Harrison Kinnard Sally Todd, sister; married Jack Johnson Mary Todd, sister; married Thomas Viars Zeph Todd - married a Colter (not sure if this is a sister of brother). (could be Zephora?) Catherine Todd - sister, married Taswell Gadd.
hope this helps i would double check this against census records..but i am pretty sure that Caleb Todd marrie twiceifnot three times.