This might be a bit of a stretch. My college roommate's grandmother was a Duffy from Monaghan. Her uncle was Hugh Duffy but he was a priest (I don't know the order). She also had 2 aunts (Duffy) who were Sisters of Mercy. They migrated to the States from Monaghan and eventually settled in Baltimore. Hugh Duffy must have been an interesting character because they always told stories about him - not always the most flattering. I don't know much else about them. But the Sisters of Mercy keep a family record of each member of the order at the Convent in Dublin where the order started. It may be worth inquiring there. Good Luck