"Israel" may have been the boy's name, or maybe not, possibly depending on whether your great-grandmother had had a son named Israel. You might want to check whether you had a great-uncle Israel who may have died in the old country, or arrived earlier. This strategy for "fooling" Immigration to the US wasn't rare, and I can't think of any reason why immigration to Canada would have been that much different.
My great-grandparents brought two unrelated young women to America. They posed as my grandmother's older sisters, and were listed under names that were already borne by her actual sisters. They were young enough that my mother, born a dozen years later, knew them. We had a picture of them with my grandparents, and Grandma explained what they had done.
