I don't know that I would want to send wedding films across the international border between the US and Canada - twice!
If you do, you would most likely be looking at expensive shipping and/or substantial delays. Canada Border Services may very well charge, at a minimum, HST on the photofinishing/scanning charges and are probably entitled to charge it on the original value of the film as well!
To protect yourself, you most likely need to declare the transaction as commercial, and that could end up costing time and money and additional paperwork.
Have you investigated other local scanning options?