If you travel 1st class (also interrail), you can choose your seat on the TGV, normally.
Due to the fact that SNCF no longer makes it possible to book domestic train journeys online in France for Interrail, I (temporarily? ) have the following question:
If you contact the call center of SNCB INTERNATIONAL in Belgium, 0.30 euros/min(!) , would they also be able to book the desired seat or not?
I think I've done it once, but it took a lot of effort.