I also noted this in the census info:

1881 - There is no John Ridgeway Watt listed as being born John & Anne Watts with son Arthur & Daniel

Class: RG11; Piece: 5596; Folio: 57; Page: 22; Line: ; GSU roll: 1342344.
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1881- John R Watts (age 3) shows up living with grandparents Daniel & Anne Teare - he may have been born to daughter Catharine Teare (age 20) listed in this census

Class: RG11; Piece: 5596; Folio: 43; Page: 19; Line: ; GSU roll: 1342344.
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1891 - No John Ridgeway Watt - Anne Teares - son Arthur, Daniel & daughter Phoebe listed - husband John Edward Watt is in America according to census
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1901 - Husband John back in Patrick - children Arthur, Daniel & Phoebe listed
Class: RG13; Piece: 5306; Folio: 154; Page: 15.

Class: RG12; Piece: 4682; Folio 59; Page 12; GSU roll: 6099792.
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More than likely John Ridgeway Watt is illigit, so date of 26 May 1878 is correct as listed in the Canadian WWI. Also the Canadian WWI doc lists place of birth as Douglas and not Patrick as stated in the 1881 - 1901 census info in previous post.

Only other way to determine would be to find a record of marriage to wife Sarah listed in the Canadian WWI document.

Tim