Hello Pueckoawaick49
Please kindly note, the GPX is not operated by SBB yet by the privately owned company MOB - Compagnie du Chemin de Fer Montreux Oberland bernois. Our assistance in the SBB Community is therefore limited to ticketing questions. For other questions you would have to contact MOB:
https://support.mob.ch/hc/en-ch/
For each adult, you can purchase a non-refundable Saver Day Pass for CHF 88 (1st class). The cost is raising the nearer the travel date, you should purchase it as soon as practical.
To do so, simply select the route From: Interlaken Ost to Montreux and choose any direct PE train. The Saver Day Pass is good for any PE train on that day. In fact, it offers unlimited travel on any Swiss public transport service on that day.
Note: Point-to-point tickets from the SBB ticket shop are not valid on the GPX train, day passes are.


Please kindly note that the Saver Day Pass requires your passport or ID (no copies, no photos) upon ticket check.
Please let us know if you have got more ticket queries.
Kind regards,
Roland