Thank you for all of your sugestions Sue,

I have the details of her trial, her convict indent (including a note that she brought 2 girls and a son with her and left a son behind on the IoM). I have her death certificate in Sydney few details other than name, age, birth in Ireland. no husband's name no childrens names, although she lived with one daughter in Sydney and was sentenced at Castle Rushen along with a son, Thomas, who I have also found a Ticket of Leave for.
I have her Ticket of Leave and her Certificate of Freedom.
I have a letter from White Hall saying she could take the three children with her.
Her daughter's marriage gives no details of her parents (She was married in Sydney by the notorious Rev. Fullerton whose records are infamous for lack of detail).
I found Andrew through Hampton Creer (author of "Never to Return) who lives on the Island and Andrew's age together with the guardianship led me to hope that I would find something of his origins. but so far this has been a dead end like all my other searching for Sarah LYNCHEY (nee MULLEN OR MULLIN) and her husband James or Michael LYNCHEY apparently from County Down.

Cheers

Peter
Melbourne