I just enquired at the train station on my way to CDG with an Access Rail ticket.
Upgrading the train segment to 1st class is NOT possible any longer.😡
The only way is to buy a 1st class train ticket. They said the airlines are now managing the system independently from SNCF so they cannot touch the ticket.
Today is Saturday, the train is empty, so a first class ticket was only 58 € last night. I bought it.
But on other days, it can be much more. It sucks to have to buy two tickets for the same trip, doesn't it?
Why doesn't AF offer the choice of 1st or 2nd class for the rail portion?