From the 1852 census for Ancaster, Wentworth County, Ontario:
http://automatedgenealogy.com/census52/SplitView.jsp?id=24312It appears Reuben's full name may have been John Reuben Porter. John's wife is listed as Mariah on this census.
From 1861 census for Ancaster:
John Porter, labourer, born England, 42
Maria Porter, born England, 30
Reuben Porter, born Upper Canada, 9
Jane Porter, born Upper Canada, 7
Freman Porter, born Upper Canada, 6
Emily Porter, born Upper Canada, 5
Carolin Porter, born Upper Canada, 4
William Porter, born Upper Canada, 1
From 1871 census for Ancaster:
http://www.rootschat.com/links/0f3s/Anna Maria Porter is listed as a widow and Reuben is not with the family.
I know Freeman's mother is listed as Elmira on his marriage registration but this does appear to be the correct family based on the children's names you provided.
Jacquie