Any flights via Montreal?
mh...if you change airlines...you shouldnt need a visa if your final destin. is toronto. sry, dont know that one. that depends if you need a visa in general. some countries are visa excempt.
is it a "big change"? i mean, some airlines do codesharing...so, different airlines, but they still work together, like British Airways and American Airlines for example, change of airlines, but luggage will be transferred automatically, since they are affiliated with each other.
Where i came back to Canada from Frankfurt via london, it was british airways to london, then American Airlines to Montreal. that was fine. Another flight was Airtransat to Toronto, pickup luggage and change for Westjet to montreal.
sry, cant help you much with that one.
big change"