I gave up and bought a 2nd class railpass through RailEurope for reasons that are confidential. someone else is footing the bill.

I realize I'll need reservations for each leg. how flexible is SNCF about these? if I book one (2nd class) that I end up missing due to a late flight are they going to give me a hard time or just let me rebook onto the next train?

what if I need to change a date, say going back to Paris a day early or into GdL instead of CDG TGV?

TIA,
benzguy80