RolandP Hello.
I didn’t mean an earlier train in Zermatt, but a later train from Brig to Milan (at 15:44).
I made a test and I obtained these results:
1 × Discounted International Extension Ticket, Zermatt – Brig Bahnhofplatz
Valid: We, 15.05.2024
Departure time: 13:13
CHF 18.60
1 × ADULT/STANDARD, Brig – Milano Centrale
Valid: We, 15.05.2024
Departure time: 14:44
CHF 39.00
The ticket for Italy is STANDARD, it is exchangeable.
In 1st class, SMART2 tickets are also available, they are exchangeable with a surcharge (upgrade to STANDARD price).
In this case, we have a mix of non-flexible tickets for Switzerland and semi-flexible or full flexible tickets for Italy.
The ticket for Italy (Brig - Milano C) has a PNR code. It is possible to install the Trenitalia app and load this ticket with the PNR code and the mail address. After this, it is also possible to manage the ticket in Trenitalia app and see if the ticket is really exchangeable or not.
Be aware that if you change a reservation in Trenitalia app, the ticket is no more refundable. I think that the vendor (SBB or other) loses the control of the ticket.
Kind regards
Daniel