If you were to ask BA now they will say no, and point out it's a consequential loss at your end, maybe your insurers will pick up the bill. And you've been given more than 2 weeks notice, you could have a full refund, and BA may be ok to move your return flight back a day.

On the other hand if you just submit the hotel and meals billl to via the Portal after travel, it may well be paid. If BAH then different rules apply. It's a bit of a stretch for EC261 but between Montréal, Consumer Rights Act and general contract law, BA may well be on the hook for this.

This assumes you cannot go some other way to your destination on the originally booked day of travel, and we don't have enough information on that key point.