Who is Mary Jane Morkan from The Dead and what is their importance?

Mary Jane is Gabriel Conroy's cousin. She is the daughter of the now deceased Pat Morkan, who was the brother of Kate and Julia. Mary Jane moved in with her two aunts after her father died. She plays the organ on "Haddington Road," which is the conversational name for a Roman Catholic church. She is a graduate of the Royal Academy of Music and teaches children from upper-class families.