Tours to Paris on Train Ticket Change Affect Final Leg of Ticket?

I don't really understand what tickets/routes you have booked, but missing the first leg of a flight plan usually does invalidate the later legs. If a TGV ticket was included in the air itinerary/booking, an airline won't have a record of whether or not you boarded a train.

It's the third of four legs I would miss. I fly Air France Berlin to Paris and then the booking then ticketed me on SNCF to Tours. It is the return to Paris leg on SNCF that I may want to change to an earlier date, but then use the original Air France Paris back to Berlin. That's exactly what I'm wondering if they'd notice I didn't use the return train portion. I could just book another train back. The small print at the end of the ticket does say the ticket is only valid if used in full and on the dates indicated. So if I change to an earlier train back to Paris, I worry I may lose the flight portion back to Berlin.

You need to ask Air France.

If I understand your question and this is a very big IF. You have a flight from Tours to Berlin with a stop/plane change in Paris and you want to get on in Paris. How are you going to get the guy out of your seat who now has your seat from Tours? Seriously, if you do not board in Tours you are consider a "No Show" and your seat is given to someone else. Why fly with an empty seat when you can put a paying passenger in it? Since you didn't show up in Tours why would they assume you would show up in Paris. So they sold that seat to someone also. Your are finished. You need another plan.

It's confusing precisely because it's a train and a plane ticket. If I don't use the train from Tours to Paris that day, can I get on the plane in Paris to Berlin?
Thanks for your advice all!

I understand that this is the Air France combo ticket, sold when the second leg of the trip is better served by train than plane. If your check in is in Tours and your luggage is transferred for you by AF, then you will certainly be considered a no-show. This is how combo tickets usually work. SNCF, the train service has its own check in and waiting area staffed by Air France personnel in the CDG airport train station. For example, if arriving in Paris by plane and transferring to a train for the rest of your trip on the Air France combo ticket, your checked luggage would be transferred for you. How it works in the opposite direction, toward the airport, I don't know. If you call Air France to ask, why don't you post the answer so everyone will know.

Yes, Bets, you are correct..it's a combo ticket, a fairly new concept it seems because several Air France agents were perplexed by how to change it. Well, non, one leg cannot be altered, alas. About the bag transfers, I was told I have to check in the bag both ways(plane to train connect and vice versa) myself-there is no transfer. I plan to call again because it your plane to train transfer seems to make more sense. I'll try another agent and see what answer I get. If not, I'll let you all know after I experience it! Thanks for help all!