Alan Jackson told me the marriage register reference for Isaac Frederick is Numbered 12726-93 in the Ontario marriage register 1873-1910.

Not really sure that Isaac died in 1937. His granddaughter Beverly Knibbs thinks that she was about 7 years of age when he died. Beverly, we know, was born in 1930.
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We can see Isaac in 1900 living at 401, Ninth Street at Niagara Falls City, Niagara, New York with his wife, daughter and mother:
Isaac Knibbs Head Aug 1868 New York, Plummer and ???
Ada D Knibbs Wife June 1874 Canada
Alace M Knibbs Daughter Sept 1894 New York
Mary Knibbs Mother January 1833 New York
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From the 1920 New York State Federal Census for 1920 we can see Isaac living at Pomfret, Chautauqua, New York.
Isaac F KNIBBS Head 50 New York Sheet Metal Worker
Ada D KNIBBS Wife 45 Canada
Frederick KNIBBS Son 15 New York
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We can also see Isaac, his wife, his son Frederick, daughter-in-law Florence, and granddaughter Beverley, living at Warren, Warren County. I believe this was Warren County, PA.
Isaac F Knibbs Warren, b. abt1870
Ada D Knibbs Warren, b. abt 1876
Fred H Knibbs Warren, b. abt 1904
Florence M Knibbs Warren, b. abt 1906
Beverley N Knibbs b. abt 1930

I don't know if these were all part of the same household or just living in the same town.

Family stories have it that Ada's family is descended from General William Howe, Commander-in-Chief of the British Army in America, 1775-1778. He was born in England on August 10, 1729. His grandmother had been the mistress of King George I, which made him and his two brothers King George III's illegitimate uncles.
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I believe the following shows Ada living with her family at Clifton, Welland, Ontario, Canada at the 1881 census:
Edward HOWE M Male 51 England Seabur..
Sarah HOWE M Female 48 England
William H. HOWE S Male 22 O Cabman
Edward HOWE S Male 20 O Cabman
James HOWE S Male 18 O
Sarah I. HOWE S Female 16 O
Elizabeth L. HOWE S Female 11 O
Rosenia HOWE S Female 9 O
Ada D. HOWE S Female 7 O