Do I need to take the train from Brussels?
I was just looking at some prices for La Premiere to New York and saw I could book BRU-CDG-DCA-NYC for a nice saving. The BRU-CDG leg is by train. Obviously, if I was using a feeder flight from somewhere they would see if I hadn't taken that flight and I'd lose the subsequent legs, but is that the same with the train? Surely there is no info transfer to say I had (or hadn't) actually taken the train.
(I assume I'm not the first to ask this but search didn't bring up an answer).