Mary Ann Kelly : Short Biography

Hello, I am trying to find the correct baptism for my ancestor Mary Ann (or Mary Anne) Kelly. She was born circa 1839 in Rathangan, Kildare (birthplace listed on her children's birth certificates in Australia). A few years ago I had Kildare Genealogy Centre conduct research for me to try and find Mary Ann's baptism, but even though the search could be narrowed down to Rathangan, there was more than one Mary Ann(e) Kelly (or variant like Mary, Marian) baptised in Rathangan around the time she was born. 

There were two baptisms that are the most likely - 

Marian Kelly, baptised 8 September 1839, daughter of John Kelly and Mary Hoey; 

Mary Kelly, baptised 14 March 1841, daughter of Henry Kelly and Ann Cassidy. 

My Mary Ann Kelly emigrated to Australia on 16 September 1862 from Queenstown (Cork) on board the ship Duke of Newcastle and arrived in Queensland, Australia on 30 Dec 1862. So I am wondering if there is anyone who may be descended from the Marian Kelly or Mary Kelly whose baptisms are listed above and who may have remained in Ireland, married and died there, and can therefore be ruled out as being my Mary Ann Kelly who went to Australia. My ancestor Mary Ann Kelly married Michael O'Neill shortly after her arrival in Australia and their eldest child was born on 3 January 1864. Unfortunately there is no record of their marriage so I cannot find out Mary Ann's parents names from a marriage certificate. 

Has anyone found a marriage and/or death (either as a child or as an adult) of either of the people whose baptisms I've listed above? 

Mary Ann died on 10 July 1925 in Sydney, New South Wales, Australia. Her death certificate lists her age as 86, making her birth year around 1839, however the age given by the informant (son-in-law) may not have been correct. If it was correct then the baptism in 1839 listed above may be the correct one. There is also an application for a pension record in Queensland for Mary Ann on 1 July 1908 and her age is listed as 66 and Mary Ann would have given her age herself. This would make her birth year 1841/1842 so maybe the baptism in 1841 above is correct (although as the baptism was in March that would have made her age 67 in July 1908). 

Any help would be greatly appreciated! Thank you very much,

John Gaven