Sorry to drag up a very old thread, but I've been doing some family research and found some additional details that could help the search - so wanted to put it all together. in the hope the original posted might see it and we can collaborate on trying to figure it all out.
My connection is with Peter's sister Mary - she ended up on arrival moving to Bathurst, New South Wales, Australia where she lived for the rest of her life.
Her first marriage was to a Charles Philip Carman in 1843 (NSW Births Death and Marriages 3880/1843) - he was my great (x4) Grandfather. After his death she married again (John McDonnell), and lived to 1901 and is buried at Bathurst. - see attached. That page from Australian Cemeteries lists her parents as a Mary Ellen Hogan and Dennis Higgins. However, her death certificate has her parents names as Ellen and Dennis. Interestingly, according to the death notice in the paper she was 84 - making her born in 1817, and listed as born in Queen's County rather than Tipperary. But others have her listed a bit younger at around 81...
Just to make it all the more confusing - her brother Paul Higgins also ended up in Bathurst - he died on 18 August 1891 (available on National Advocate, Bathurst 20 August 1891 - see Trove)
On his NSW Births Deaths and Marriages short form it also has parents names of Dennis and Ellen for - but as per this page on the cemeteries page, it has them listed as a Dennis Higgins and a Ellen Dooley. His calculated birth date of 1816 makes sense alongside Mary's Birthdate of 1817
Anyway, a few more clues to the puzzle. I will keep digging, but wonder if any of those extra details/potential variations will do anything to help with searching :)
Cheers
Matt
PS: I have the external links for the pictures I can add but when I tried to add them I got a 'you are not authorised to add external links'.