Originally Posted by
tbaiyun
Last year, I used miles to upgrade a friend of mine travelling in W+Y (YUL-CDG-VIE) in advance (not OLCI upgrade); and only the TATL segment was upgraded that the itinerary becomes YUL-CDG in J and CDG-VIE in Y; he was able to get into the 2F lounge at CDG at transfer by scanning the CDG-VIE boarding pass.
That's why I advised the OP to try anyway, and report back.
Even when it's not officially required, AF and KL will sometimes bend the rules. If the lounge is packed, however, there is no chance.