Hi Mo,
if this is 'my' Donald Duff then he and his first wife, Janet 'Jessie' Murray, had the following, Donald (Daniel?), Alexander, George, Catherine, William, Ann, Janet, Margaret & Robert. Janet died and Donald then married Isabella Gunn abt 1844 and they had the following: Bell, Ann & Johanna. Some offspring from each of the two familes came to Australia and my husband's Granfather is descended from Janet of the first family and his Grandfather was descended from Ann of the second family.
I know, very confusing!!
If you would like to share some info about this family I would like to communicate directly so we could email documents, etc.
Cheers, Jean.