Thomas Callaghan 1849 1909 Married to Mary Holmes Died Dec 1880 Ireland

I have not been able to find any information about these 2 paternal great grandparents. Mary Holmes died after giving birth to my grandmother, Winnifred Callaghan (Chambers). I have the birth certificate (birth in Rathoma County Mayo) and know most of the history from 1880 until now. I can't find any information about either Thomas nor Mary before 1880. I would like to find out their parents and siblings and where they were born. Can anyone help?

Thomas immigrated to Iowa and brought 2 of the daughters. The youngest appears to be a twin to my grandmother. My grandmother was left behind and raised by relatives. Thomas Callaghan paid the boat trip for Winnifred after she was a young woman. She married Michael Thomas Chambers in Chicago. Their oldest son was my father.