i hardly think there are two christopher donnellys living in canberra at any time. a descendant of christopher donnelly and mary mcdonald said that mary went to live with her daughter in bowral once christopher got kicked by the horse and died.
Not sure that I have further opportunity to help your quest, my offline resources are quite extensive and concentrate on NSW in the 19th century, but at the moment it is more important for me that I get back onto my work commitments.
I urge you to quietly take the time to read back over all the posts on this thread, and also to remove the name of the living person mentioned by you.
Good hunting,
JM