Mary O'Brien born 17 Aug 1826 Thurles

My great grandmother Mary O'Brien died in Australia.  She married  Andrew Bourke from Kilkenny.  They married in Australia. In her obituary it was stated that her father was Thomas O'Brien and that she was born in Thurles and raised in Carrick-on-Suir.   Other information available states her mother was Cecilia Lanagan and that  Mary was the eldest child of Thomas and Cecilia (Lanigan) O'Brien and two more children were born, Thomas junior in 1828 and Kitty O'Brien in 1830.  I have all three baptisms.  I have been unable to establish any information on the O'Brien side, however, the Australian obituary for Mary states that she was the neice of Dr J. O'Brien and the grandaughter of Councillor Lanigan of Templemore.   As Mary was a Female Famine Orphan who was sent to Australia in 1848 I doubted that this could be correct as this Lanigan family would surely  have cared for her if her parents had predeceased her, as this Lanigan family seem to be

 an established family who appear to be gentry and with property and therefore would have most likely have been able to look after their young relative if she was orphaned, unless of course there was a family dispute between the two families.   I  am presuming that Councillor Lanigan was the J.P., barrister and Member of Parliament that I have found when googling Lanigan and Templemore but maybe they are two different people.  I would appreciate any help with this conundrum.  I have searched for a "Cecilia Lanagan/Lanigan" for thirty years with no success.  I might add that Mary Bourke nee O'Brien was widowed young and became a successful business owner and provided well for her children until her death at a very ripe old age in Mount Gambier in South Australia.  Her husband had been a Squatter before his death and the family moved between Portland in Victoria and Mount Gambier across the border into South Australia.  In immigration records it is stated that Mary could not read or write but I do not think this is correct as other errors have been found in these records.  I doubt that she could have become a shopowner without these skills.  Her spinster daughter was well educated and ran a Catholic School for over fifty years in Mount Gambier and I believer her early education was from  her mother.   Any advice or help would be most welcome.

Regards, Cheryl Kerr, Warragul, Victoria, Australia