Hi Cam
Have had a bit of a 'rummage around’ and have to say that I can't find a daughter called Ann of Ann and Richard Callaby. That doesn't mean there wasn't one, but I can't find her. I checked your list of children of Ann and Richard and I have all of those (minus Ann) plus an Elizabeth born in 1842 (later became Cavanough).
In relation to Ann Howard nee Callaby, John Howard was her husband (if you have a look on ancestory.com you will be able to find her headstone which lists her husband as John. Her son Martin is also mentioned on the headstone and died around the same time as her). Ann’s NSW BDM Record number 18521/1929 lists her father’s name as John. It doesn’t list her mother as unknown but lists her age and place of death in that space. I think the only thing is to get hold of the certificate as there has obviously been a problem with transcription.
Re Peter Charles McBow: all his convict records state his year of birth as around 1820, muster records online and one or two I found at the NSW State Library confirm that too. His certificate of freedom gives his birth year as 1820. His marriage certificate to Maria Callaby in 1857 sees him stating his age as 38. However, after that he seemed to ‘loose’ a few years with the birth of each child and indeed would state that he was around 10 years younger than he really was and state a different place of origin. The only constant is Maria’s age and the names of children etc. It seems Maria carried on the ‘tradition’ on his death certificate. There could be some other sensible explanation but I have yet to find it!
Cheers
g