A Thomas Andrews of Chatham County, who died in 1779, names a wife Susannah and 4 children in his will: John, Thomas, William, and Mary. Not sure what your dates refer to in your message. If they are birth dates, then perhaps one of the 3 males had a child named David in 1795. But I don't know for sure. If the dates are death dates, then the answer to your first question is probably NO. As to the second question on the children of David Edwards and Margaret Andrews, the children named in the message from JanLeeLam confirms my information. I don't see any of your names mentioned, plus their dates conflict with children already listed. So I'd say Marjorie and Sarah/Sally are not from this line.