I found the baptism for Catherine in Notre Dame Basilica in Montreal; unfortunately, it is almost unreadable, except that her father's name was Michael, and was dated in 1870.
Baptism for younger brother, Patrick James, was in St. Brigid's in Montreal; names parents as Michael Kenny and Ann McDoole.
Marriage of Michael Kenny and Ann McDool in Notre Dame Basilica:
8 September 1869, Michael Kenny, domiciled in this parish, son of age of John Kenny and Mary Quinn, of Quebec, and Ann McDool, domiciled in this parish, daughter of age of deceased Patrick McDool, laborer, and of deceased Catherine Mullins, of the County of Monaghan in Ireland.
Now the problem I see is that Katherine Kenny and George Shields were married in February 1901, and the Catherine above is still living at home with her parents in Montreal in the 1901 Canadian Census, which was not taken until later. It is possible that there are two different Catherines with parents named Michael & Annie, especially since Katherine gives her birth place as Newfoundland.