Have you looked under the resources section for Canada. Under Nova Scotia research, you will find some amazing links that you may be able to pursue.
I'm not sure exactly where you got the information on the deaths in 1872 for Ellen McLeod and William Robertson but they are on novascotiagenealogy.com but the information for Ellen McLeod is a bit confusing. The year 1872, book 1813, page 113, number 101 and 102.
William Robertson, age 80, married, born in Scotland, Parents name Robert and Eliz ? Robertson, occupation Farmer
d. 12 May 1872, Glengarry, old age, informant was Ellen Robertson.
Ellen McLeod, age 78?, married, born in Scotland, parents William and Ellen Robertson, D. 26 May 1872, Glengarry, occupation farmer, informant was Ellen Robertson.
It is possible that McLeod is the maiden name and not the married name but that would have been unusual in Nova Scotia at that time. Under the section for parent's name, occupation and whether alive or dead, the information for Ellen McLeod is William and Ellen Robertson. These deaths are definitely in the Hopewell area so I would definitely follow up on these.