I had not thought to check on the Homestead filings, and will give that a try.
The family went rather freely back and forth over the border, and I do know they lived in a couple of locations in Montana: first in the Lewiston area, then in the Glasgow area. Isobel, George's older sister, was around 14 at the time of George's death and was pretty specific about where they were living just prior to this, so I am focusing on Alberta and Saskatchwan as the possible locations for the death and burial records for George and Adelaide.
Isabel does not remember the name of the convent, but her recollection is that her mother died, they were sent to live in a convent school, then little George was killed in this horrible accident, then she ran away to join her older sister and her family who were at that time living in Arrows Lake BC.
I have recently found a George Adam buried in the Catholic Section of the KIn Coulee Cemetery in Medicine Hat (no birth or death dates and no age) who was buried August 16, 1913. I emailed an inquiry to St Patrick's Church there in Medicine Hat, but have not yet received a reply.
I am still trying to figure out where the convent school was possibly located. I checked out the one in Pincher Creek a while back, but their records were destroyed in a fire.
I have found one Border Crossing for Julie and Jeremie Adam from 1917, and entry into the US was denied on that occasion. They were on the Medicine Hat census in 1916 but could very well have sneaked back across the border. They were getting up there in years, however, and they had married children living in Alberta, so it seems like they might have just stayed.