There has been much research on the Morrisby family, as Grace was the daughter of James Morrisby, a first fleeter who lived on Norfolk Is for a number of years. You may find it relatively easy to prove/disprove this relationship in your family tree. Irene Schaffer of Tasmania has written a number of books/articles on early Tasmanians. Her website http://members.optusnet.com.au/~schafferi/http://members.optusnet.com.au/~schafferi/ gives details. Of particular interest would be Private George Smith of His Majesty’s Royal Marines 1804 This would no doubt give the required details of the Grace and George family.