Just wanted to pass along a website that you might find interesting:
I'm not sure from your message exactly where your relative signed up in Canada, but if it was in Calgary you might find this website interesting:www.rcplayfair.ca
This site features letters that Ross Playfair of the 50th Battalion of the CEF wrote to his wife during WWI and it also features some of the battalion's war diaries.
Many of the soldiers of the 50th battalion either were from Calgary or they signed up in Calgary but even if your relative wasn't with this particular battalion, you might find this to be an informative website since it gives an interesting perspective on WWI and it is also a wonderful love story about Ross and his wife, although none of her letters to him survive.
Good luck in your search.