We back up a little and return to 1871 and the Canadian Census which features the family of Archibald and Mary McDonell, the great grandparents of Keith.
As you can see John and John Alexander are missing. These are the first two sons born to Archie and Mary. We can only assume that they did not survive. There is a possibility that they are buried in Sheensboro. http://en.wikipedia.org/wiki/Sheenboro,_Quebec
Source: 1871 Canadian Census, Chichester, Pontiac Co., Quebec #C10025, page 23 and 24 Dist #91 or FHL#0493443.
Line 16-20 pg. 23 Dwelling 19 Family 19 – McDonell, Archbld, male, age 39, Born Quebec, R. Catholic, Scotch, Farmer, Married, unable to read. McDonald, Mary, female, age 36, born Quebec, R. Catholic, Scotch, married, unable to write. McDonald, Angus, male, age 7, born Quebec, R. Catholic, Scotch, going to school. McDonald, Ronald, Male, age 4, born Quebec, R. Catholic, Scotch. Next page # 24 line 1 and 2: McDonald, John Archy, male, [ ] born Quebec, R. Catholic, Scotch. McDonell, Ellen, female, 3/12, Dec, born Quebec, R. Catholic, Scotch.
Here is an interesting link to a website that gives cemetery information for a wide variety of locations including Quebec.
So the Canadian Census of 1871 supports the theory that John and John Alexander did not survive because they are not listed; however, more research is needed to see if their burials can be found.