Unfortunately, points can only be earned from merchants that are listed on the ShopMyWay site (see link below for list of merchants). We aren't able to control where the items are shipped from.
However, at the bottom of the ShopMyWay site, there is a “contact us” link and one of the options is to contact ShopMyWay to suggest a new merchant.
Hope this helps. Thanks for reaching out!
I am also in Canada and used this site a couple of times in the last year. I lucked into decent shipping costs despite the international rates and I was pleased to see that my points actually posted without any trouble. I don't have extensive experience with the site, but so far so good.