Marks family of Birr

Can anyone kindly tell me what happened to the Marks family of Birr (then Kings Co., now Offaly Co.) who appear in the surviving fragment of the 1821 Irish Census? Timothy Marks 48 butcher, his wife Mary 46, and their children Michael 24 butcher, John 13, James 11, Elizabeth 8 and Sarah (Sally) 6. Possibly Elizabeth is my great-grandmother Eliza Marks who left Ireland for Australia (where I am) as an assisted migrant in 1835, sponsored by the London Emigration Committee: Eliza said she was born in Kings County, Ireland and was RC; she also said her father was a butcher. Timothy is a rather unusual name, making tracking him down marginally easier. Any help would be much appreciated.