Originally Posted by
GS4ACUSA
Interesting. I've seen folks traveling from XXX-YYZ-YUL stand by for XXX-YUL without issue. I'll have to check what the actual policy is in this case!
But that's all AC metal.
AC expected the money for a XXX-YUL fare, and they receive it all either way.
For
YYZ-FRA-ZRH, LH expects some money.
There's nothing stopping AC from lifting the first coupon and throwing you on YYZ-ZRH (and it happens all the time in IRROPS), but I suspect the accounting becomes a mess.