Originally Posted by
Adam1222
Changing departure countries is tricky, but the OP should be able to get YVR-SEA-CDG (or YVR-MSP/SLC-CDG)
Connecting through US will involve same fares and currency as non-stop from Canada, but will incur about $38CAD in additional fees (Customs/Immigrations/Aphis/TSA). While DL can potentially waive original fare class availability when changing flights due to schedule changes, I wouldn't necessarily assume they will waive these additional mandatory US government fees.