Like many of us, you may have pre-booked several tickets prior to the increase in award "prices" at the end of the year which were applied to Business Class FF seats on Cdn+. Amex Rewards members benefitted from a 10% to 15% discount in the number of points required for such tickets, so a Business Class North America was 27K rather than 35K. (The regular "price" rose to 40K in January, though was discounted to 30K under the now-defunct Amex Rewards program.)
I had to make changes to my itinerary on one of these tickets today and learned the following which might be of interest to others:
1. Any changed flights must be on CP metal. AC flights, even codeshares, cannot be used.
2. If there are any routing changes that require a re-issue (other than a connection versus a non-stop or direct flight), then this can only be done at the current "price", so an additional 13K will be deducted from your account.
Not a complaint, just a heads-up in case any of you are in the same boat.
Otherwise, I had no problem otherwise booking the domestic flights I wanted in Business Class even in July from CP's inventory on its own flights, albeit with an AC shuttle between YUL and YYZ.