Catherine was also known as Sister Mary Francis of Assisi. She was baptised on 22 Nov 1829 in Ballymore Parish, Co. Westmeath, Ireland. After arriving in Montreal in 1841, Catherine, Hugh and her sister Ann were confronted with the death of their mother, two months prior. Catherine, Elizabeth and Mary were sent to boarding school at Pointe aux Tremble, where they remained four years with the Congregation of Notre Dame (1841-1845). When their father, Thomas, heard of Mother Mary Rose Durocher's boarding school at Longueuil, with the newly formed Sisters of the Holy Names of Jesus and Mary, he decided to place his daughters there. The two girls were there from 1845 until their entry to the convent in 1847, taking their vows in the following years. A biography was written about them by Sister Mary Gilbert, SNJM (Mary Hughes) in Montreal, between 1910 and 1921. It is attached below on the bottom of this page in pdf.
Sisters of the Holy Names of Jesus and MaryIn 1840s Montreal, Mary Rose Durocher (later Mother Marie Rose) was an educated woman with several siblings already serving the Church. She perceived that young women were not being educated for the challenges of life, and in 1844 she founded a new congregation and school in Longueuil, Montreal and named it the Sisters of the Holy Names of Jesus and Mary. The order has established schools and colleges for girls throughout Canada and the United States. Longueuil is now part of metropolitan Montreal.The O’Neill sisters were among the first to attend the boarding school, and then to make their vows. Catherine, having never known her own mother, understandably welcomed the community of nuns. She took her vows at age seventeen, then worked as a teacher and a nurse. Catherine became Sister Mary Francis of Assisi (in French, Soeur Marie Francois d’Assisium). Mary, her younger sister by four years, was eager to follow in her footsteps. The superiours were hesitant but she was able to obtain her father’s blessing. There are several stories about her earnestness. One was when she was worried what would happen to her pet canary(she was told it was all right to bring it), or she denied herself jam on her bread (the sisters said she did not have to deny herself so much). She was mischievous—not wanting to hide her curls and letting her bonnet fall off her head. In time found the balance she needed.