Hello Martha, I see from my notes that we traded emails on this same family back in 2007. Since then I have come to this ASSUMPTION: On the 1880 Columbia Co census, we find this:
1870 Columbia Co FL Census- Lake City- Dwl # 1065/1065 GILLESPIE, Martha, 42, keeping house, $ 475, GA, XX GILLISPIE, Fairley, 18, farm laborer, FL GILLESPIE, Oregon, 17, domestic servt., FL GILLESPIE, Virginia, 16, at home, FL GILLESPIE, William, 15, farm laborer, FL XX GILLESPIE, Nancy, 13, at home, FL XX GILLESPIE, Dock, 12, farm laborer, FL, XX GILLESPIE, Oregon, 2/12, at home, FL, born April
It my assumption that the Oregon child born in April 1870 has to be your grandmother Martha. Same birthdate and same family.
Oregon Gillespie did marry James Edward Prescott in 1873 so their 10 children would have been half-sibling to Martha A. (Oregon) Gillespie Smith. I have no idea how you could find out who the father of Martha would be if it's not it your family Bible.
I'll work on the Smith/Carver question you presented. I don't have any information on this line. What makes you think she may have had a daughter before marrying Isaac Smith?