The following is research undertaken to connect Mary Brennan, Australia 1850 with her family in Boyle, Co. Roscommon. It is incomplete.
A search of familysearch.org for the time period 1820 to 1850 finds 6 couples by the name of John and Mary Brennan with some of their children. (The mothers' surnames are found in a variety of spelling combinations, for simplicity sake I have only listed one form)
The marriages listed were found on ancestry.com.
John Brennan & Mary Crine, ( possible marriage April 25, 1825, Boyle) children Patrick 1826, Bridget 1828, Michael 1828
John Brennan & Mary McCormic, (possible marriage July 27, 1825, Boyle) child Mary 1826 (Had Mary not been such a common name I would be more excited about this return)
John Brennan & Mary Mcdermott, (possible marriage Oct. 14, 1827, Boyle) children Honoria 1823, Bernard 1828, Jacob 1836
John Brennan & Mary Doyle, children Patrick 1820, Patrick 1832
John Brennan & Mary Brannegin, children Anna 1836, Matthew 1838
John Brennan & Mary Cregan, children Margaret 1835, John 1835
By 1901, there are 22 Brennan families recorded in the DED of Boyle, Co. Roscommon. Listed below are the Heads of Households.
In Boyle Rural;
Michael, John, Thomas, Mary, Michael, Domnick, Patrick, Thomas, Patrick, Owen, Michael, Darby, Maria, John, Roger
In Boyle Urban:
Sarah, James, Bridget, Patrick, Mary, James, Thomas
1901 Irish Census
Australian research Trevor McClaughlin irishfaminememorial.org