The informant on Margaret's birth certificate was a Mrs. Gray, any relation?  the 1901 census for Dryden states her year of birth is 1870.

Registration # 004516, Oct 10, 1869. Margaret McMILLAN, female. Father: John McMILLAN, farmer. Mother: Kitty Ann NODWELL. Informant: John McMILLAN, farmer, Erin. Registered: 26 Oct 1869. Accoucheur: Mrs. Grey. Register: Wm Tyler, County Wellington.