I am slowly making progress on this line.
One of many remaining mysteries, however, is what became of David's wife, Margaret, nee LOGAN. She is referred to in David's 1868 will, but I can't find her neither remarrying nor dying in Victoria, as a ROLFE or similar. Maybe she went back to Tasmania, or Ireland ?
Several other researchers claim that that Margaret remarried, and died in Northcote in 1904, but I don't think that that is correct.
Nor have I been able to find a name for Margaret's first daughter, although she is referred to (nameless) in David's will.
First marriage: REGAN
Other names Margaret used: FERGUSON & JONES