Laurie: According to the Land Registry record, instrument #10745, Feb. 4, 1858. A mortgage was given to Ezra Gamble by Timothy Fralick & Maria Demille, for a 3-acre parcel, described as lot 22, concession 6, Scuog. In Jauary of 1861, the same property was sold back to Ezra Gambel by Maria Demille to release her dower rights.
If this can connect Maria to the deMills that you mention, that would be a breakthrough. the only information that I have about her is that she was a member of the Missasaugua tribe. Does that sound familiar to you?