Just because one can't resist a puzzle ...
"Still not sure how Annie Hawkins/ Heaton was involved in all this. One relative suggested that Annie's sister was the mother of Hamilton but records of him born and his mother's name are not that easy to find."
Actually, we don't know who Annie Hawkins/Heaton is at all -- this is the first mention of her in your thread! If you could explain that, it could help somebody help more.
(We actually don't even know
which "Records say he was from 'St George in the East Parish'." That is, what records you have that you have that info from. Telling everything you know and clarifying what you are really looking for is really important.)
Are Hamilton's parents not as shown in the 1911 census?
http://data2.collectionscanada.gc.ca/1911/jpg/e002066659.jpgCharles's birthdate there is given as April 1881 - yes, dang, that would be right after the 1881 census, in all likelihood.
Aha.
I have just found Charles in 1901 at Ancestry by looking for anyone in Maskinongé born in England. Charley Hacton. Lemme look for him at automatedgenealogy or collectionscanada ...
Here you go.
http://data2.collectionscanada.ca/1901/z/z003/jpg/z000149964.jpgautomatedgenealogy has him as Haeton, which is how it looks to me.
(The problem with AG is no fuzzy searches; you have to guess the spelling, and I guessed that.)
http://automatedgenealogy.com/census/ViewFrame.jsp?id=78440&highlight=22Adopted son of Leon and M. Louise Giguère, who also have a daughter ten years older.
It gives his birthdate as July 16, 1880, England.
I believe the occupaton says Ouvrier - labourer.
I think this is Virginie Dussault, aged 43, with daughters M. Louise and Berthe, as in 1911, and husband Hubert, a merchant. There is a Desaulniers family on the same page ... and a widowed 63-yr old L. Alexis Desaulniers farther down the page whom I might suspect of being her second husband. And oh look -- he is a lawyer.
http://automatedgenealogy.com/census/ViewFrame.jsp?id=78442&highlight=12(The relationships and occupations are in French, so I've given the translations.)
Both families are living in Louiseville. It's rather an odd coincidence that the enumerator named on the page where Charley appears in 1911 is Charles Eaton!