Hi Kerryn
My name is Matthew McGrath, and have GGG grandparents from Tipperary, Ireland named Patrick and Mary.
I wonder if they could be the same as yours?
My GG grandfather was born to the above in Nenagh parish, 1834. Perhaps your Catherine was his sister.
He came to Australia, and was married in East Ballarat 1867 to Honora Hogan.
Their children include Catherine, Patrick, Dennis, Michael, Matthew, Jeremiah, John, James, William, Mary)
On his maariage certificate, his mothers maiden name was Donnelly (Connelan?)
Cheers
Matt