I'm not sure, I got it from a railway person that travels a lot in Europe. My understanding is that currently, this regulation might work within one provider b

I'm not sure, I got it from a railway person that travels a lot in Europe. My understanding is that currently, this regulation might work within one provider but not on handover. If you book in DB app, and you miss the handover to TGV it doesn't work. But maybe its the case that the regulations say that it should and it simply doesn't.