I would suspect that Catharine may have been a younger sister or cousin of John O'Hearn of Maple Grove who was born in 1822 in County Kilkenny, Ireland, perhaps at Harristown or Milltown, Knocktopher.
John O'Hearn married Catharine Fenlon at St. Luke's Church in Two Rivers WI. She was a daughter of Owen Fenlon and Mary nee' Murphy of Borris, County Carlow, Ireland. I also note that there is an obituary in Maple Grove for Thomas Fenlon (died 1972) son of Thomas and Rosella nee' Sullivan Fenlon, and apparently descended from a brother of Catharine Fenlon. Thomas was married to Margaret Duggan on April 20, 1955, apparently a descendant of Jeremiah and Catharine Duggan.