You should be able to change your wife's passport in time before your trip. I just went through passport h*ll with name changes, and if you change your driver's license (or other ID required for the passport renewal), you only need to bring in the receipt that you've submitted the change as proof to Passport Canada (i.e. you don't need to wait until the new license has arrived in the mail). But you will have to fork out the extra $ for the 'rush' fee at the Passport office.