Would you be able to supply more information about the Watsons:
- Were the siblings male or female?
- Did they have wives/husbands when they immigrated or did they marry here?
- Can you give their first names and birth years?
- Do you know their occupations?

Any additional information you can give will help narrow down the search.

Also, have you checked the 1901 and 1911 censuses online (free) at
http://automatedgenealogy.com/census/index.html ? I can't check it for you without first names. There were, for example, 38 Watsons enumerated in St. Catharines/Niagara in 1901 and 32 in Welland County to the south.

Here is the only item I could find with so little to go by. It is a death notice from the St. Catharines newspaper index online at:
http://bmd.stcatharines.library.on.ca:1968/


Record Number:
17834
Record Type:
Death Notice Source Type:
Newspaper
Source Name:
St. Catharines Standard Publication Date:
January 21, 1925
Section:
n/a Page Number:
2
Event Date:
n/a
Name of Deceased:
Naylor, M. E. Mrs.
Survivors Names:
Watson, J. H. L. Mrs. (daughter)
Naylor, Arthur G. (son)
Naylor, W. Ernest (son)
Naylor, Thomas (son)
Notes:
City and Vicinity Column
Obituary
She was born in England and came to this city when a young women
Predeceased by Naylor, Thomas (husband)

Sharon
Welland, Ontario