1891 census Russell Ontario

SWAIN
Hugh, 56,
Jenny, 30
John E, 20
William, 19
Mary Ann, 22
Nathan, 13

Birth Declaration given by half sister Mrs Laura Devine on 18 Apr 1918 at Cumberland, Russell.
Hugh Swain, b 5 Dec 1890 at Cumberland, Russell; parents: Hugh Swain & Jennie O'Neil.
"I am a half sister of 62 yrs of age and seen my step mother in bed with this infant and has always been recognized as my half brother and it always family knowledge that he was born on the above date."

There is no mention of Jeremiah except on 1901 census b same date. Wonder why they weren't on 1891 census.

Marriage:

Hugh Swain, 24, farmer, s/o Hugh Swain & Jennie O'Neill, married Verlie May Scharff, 18, d/o Robt Scharff & Annie Sweeney, witn: Jerry Swain of Cumberland & Emma L Walsh of Navan, 10 Jun 1915, Cumberland, Registration # 012850.

Birth site only goes to 1909 so cannot help you out there.

Found absolutely nothing on Jeremiah. Nathan and William Swain, his half brothers, went north to Sudbury and Nipissing District so he could well have gone up there with them. He is still in Cumberland in 1915 for Hugh's wedding.
Could not find where either of them were in WW1.