The 1901 Census of Canada does not include any Seamark entries. The Census of 1911 includes 2.
Charlie, age 35, married but living as a lodger in the home of William Hayes. No evidence of other family members.
James, age 48, married but living as a lodger in the home of widowed Elizabeth Barton. No evidence of other Seamarks here. However I did find a marriage, perhaps a daughter of James:
011197-03 (Lanark Co), Thomas H. HOUSTON, 23, Almonte, Arnprior, dry goods clerk, s/o Thomas HOUSTON & Martha CLOSE, to Francis SEAMARK, 20, Arnprior, same, d/o James SEAMARK & Elizabeth GARDINER, witn: Andrew SCOTT of Toronto, B. C. SCOTT of Carleton Place, 2 November 1903 at Carleton Pl
Sorry I am unable to locate Harriet for you.
Beth