In Switzerland you don't need to make any reservations unless you want to go on the special tourist trains. On most of the tourist routes there are, however, also regional trains where no reservation is needed. You can read more about the Swiss tourist trains here:
https://www.swissactivities.com/en-ch/panoramic-trains-in-switzerland/
Hi + thanks
My question is not specific about Switzerland, but about how to plan such a round trip with multiple stopovers
Dobry den, or vecere.
It all depends on WHICH trains you want to use-and also what type of pass you both have. On the new style mobile you can do more self-serve REServations, but these all cost an additional 2€ fee.
The superfast TGV OVER the border cost a lot mor as only In FRance-so you could save money by crossing border DE-FR by local train.
For your route the FRench TGV and the Frecce and IC in IT MUST be reserved, but you do not need to do that now for over 2-3 monthes and certainly not if you can be a little flexible. More info in the country info. The INTern trains IT-Austria want a 10€ supplmt-besides the REServation.RES. for It can be done online via site of oebb.at =austrian railway, has been explained here very often.
To save money going from FR to CH: use TGV only to Mulhouse, then change to local train TER to Basel and as above, In CH its all free.
Prosime vystup te, they say now to me, but in my language
Reservations for Italy (Frecciarossa, -argento, -bianca, IC and EC) and EC/RJ/RJX from CH, A, D, SLO to Italy you can get via Austria ÖBB via tickets.oebb.at select one way ticket (NOT only seat) and at passenger the discount Interrail/Eurail Global Pass. For reservations in Austria, Germany and other countries for train without compulsory reservation you choose the only seat option of ÖBB, DB or CD.
Trenitalia high speed train Frecciarossa are part of Interrail (+10€ reservation) but not the trains Milano C.le - Paris Est. You can use the competitor SNCF TGV InOui insteed with Interrail.
For SNCF trains you can buy online only via Interrail.eu reservation service. Or calling SNCF Call Center, maybe SBB CFF FFS can sell reservations for French trains. For most central European trains it can.
To plan the trip use a general train timetable website like bahn.de or sbb.ch. And than check on the website of the train operator if the data is correct.
If you have any problems booking a train, please mention the specific train (origin, destination, date, departure time).
Thanks to everybody for their help