CDG to Brussels ticketing question
 

My daughter will be flying on UA 990 SFO-CDG, scheduled arrival 10:35 a.m. next Thursday. She intends to catch the TGV to Brussels leaving at 1:07pm, which is well beyond the recommended minimum transfer time of 90 minutes from terminal 1. Questions: should she buy a TGV ticket ahead of time? The main concern being a flight delay forcing a misconnect. If she buys ahead and misconnects, would the ticket be valid for a later departure? Are day-of tickets purchased at the station significantly more than tickets bought ahead? Is there any chance that seats would not be available on the train if she waits to buy tickets at the station? Thanks for your insight.

I've only bought tickets on Spanish high speed rail, but IME the tickets got more expensive as day of travel approached and some trains were sold out.

Strongly suspect same applies to France. Hopefully posters with more experience will chime in.

Read this page: https://www.seat61.com/France-trains...20for%20France

TGVs require reservations so theoretically they could sell out, but it's unlikely.

When you buy tickets online it should tell you whether the ticket can be changed, sometimes for a fee.

If you mean the 2nd of May, then there seems to be a Thalys train at 1214 and then a TGV train at 1307, the Thalys train is a lot faster, but the ticket can't be changed after departure, which doesn't help if you already missed the train.

The TGV has an option for a flexible ticket which says it can be changed without fee up to 2 hours after departure.

There are also additional complications if you are using a US bank card or buying on a device which appears to be located in the US (or outside of Europe at least), but the above site goes into this in detail.

TGV ticket machines basically connect to the SNCF website and use the same booking interface, and only take card.