Thanks so much. This confirms the three known daughters of William and Martha (Baker) Davidson (Sarah "Sally," Charlotte and Ginny/Jane).
William and Martha's sons Baker Davidson and Joseph Davidson had both died before 1815, leaving Andrew Baker Davidson and William Davidson, Junior. If there was truly another fifth unknown "oldest" son, then that son was probably/apparently dead by 1815.
"Robin" (Robert) Davidson who married Sarah "Sally" Davidson was from that unrelated Davidson family that I mentioned in my earlier post (and William Davidson, Junior's wife Jinny/Jane Davidson was a sister of that Robert Davidson.....the parents of Robert Davidson and his sister Jane Davidson were John Davi(d)son (died in Rockbridge about 1802) and Mary Allison).
I did not know that William Davidson, Junior took-in the McCartney children. Based on that, PERHAPS the William Davidson shown below who was on the 1820 Rockbridge census at the age of 26-45 with a "bunch" of people in his home was him after all (I had thought that the William Davidson with all of those people was another/unrelated known man named William Davidson....but maybe that was not the case). The following shows that William Davidson's census information. Could several of these people have been members of the McCartney family? Note that there were 7 people in just the age range of 16-26 alone in the home in 1820!
William Davidson 112710 - 001100