I am in the middle of booking a series of train tickets in March for my wife and me. For a particular train on March from Brussels to Amsterdam, the price is 60 € /each in standard (changeable) with no option for a non-flexible ticket. However, if I price a ticket on the exact same train from Paris to Amsterdam, the non-flexible ticket is available for 35 €. It seems like trains are learning about married segments.

So what would happen if I buy the cheaper Paris-Amsterdam ticket and just board the train in Brussels? Would my non-flexible ticket get canceled if it is not scanned onboard after the train leaves Paris?