Thanks so much for taking the time to reply. I have indeed found information since I posted this, but it doesn't agree with what you have here. It's quite possible I've mixed up the families though as you've mentioned.
What I have is a John and Grace Thompson in the 1901 Huron Township, Bruce County South, Ontario census page 10 with children Donald b 1877 (age 23), James b 1882 (age 18), Edith b 1886 (age 14) and John N b 1892 (age 9).
I also have John and Grace Thompson in the 1891 Huron Township, Bruce County West, Ontario census page 43 with Archy age 15, Daniel (Donald?) age 12, Kelty (Catherine?) age 10, James age 8 and Janet age 4.
Since it's the same township it would seem they're the same family but there are discrepancies. Grace's age is 36 in 1891 and 47 in 1901 which works well but John is 40 in 1891 and 61 in 1901 which doesn't track. Also the children's names don't track perfectly, with Edith in 1901 but Janet in 1891; Daniel/Donald may be enumerator error; Kelty may be a short form of Catherine.
I also have John and Grace in the 1881 Huron Township, Bruce County South, Ontario census page 69. John's age is listed there as 40, which agrees with the 1901 census. Grace's age is 28, which is close but not exactly the same as the other two censuses. It has Archibald, age 5, David (Donald?) age 3, and Catherine age 8 months. This seems to track well enough to be the same family.
I also have a John Thompson, age 30, in the household of Thomas and Jane Yeman in the 1871 Huron Township, Bruce County South, Ontario page 11. This fits with the age of their first child, Archibald, in 1876 and a marriage record I found for John Thomson and Grace Mcmillan in Erin, Wellington County, Ontario on 14 Jan 1875.
Grace's parents are listed on the marriage record as Donald M Mcmillan and Catherine Mcmillan. I have an 1871 census in Erin, Wellington County, Ontario, page 55, for Donald and Catherine which includes Grace, age 18, in the list of children. That age matches the 1881 census.
I have George Thomas Scott in the 1871 Huron Township, Bruce County South, Ontario census page 32. He is 1 1/2 years old, in his parent's household. Same township, same county. I have a scanned copy of the marriage license for George and Edith, in Brussels, Huron County, Ontario dated Nov 30 1911. This was supplied by my sister-in-law Cathy. Both George and Edith are listed as living in Huron Township, Bruce County, Ontario on the license. No parents are listed, but Edith would have been 25 and George would have been 42 so no parents would have been required for them to be married.
Did you look at this one and decide it wasn't as good a match as the one you listed? Can you give me census page information so I can look at those records for Jeremiah and Caroline? I don't see a Jeremiah Thompson in the 1871 Bruce County (north or south) censuses..