Which connection are you looking at ? The route to Milan can easily be done reservation-free (= full flexibility)

Usually seat reservations are not exchangeable nor refundable but maybe with the Gotthard Tunnel issue they'll be more understandable. Where did you buy it ?

Thank you for reaction - bought it at Frankfort railway station. The lady said it would be mandatory for this route.  

I reserved for Zurich- Milano 17.33 leaving Zurich,  but this is too late for the entrance of the hotel (which is also really strange). 

Now I saw for example Basel-Milano EC 153 (leaving Basel 15.03  to Milano 19.50 which is almost too late for hotel but would hope it 

She said I would have to pay new  (which is 39 euro with 2 teenagers) - global pass would block refunds basically). 

I'm really frustrated paying roundabout 1.000 for 3 global passes and being treated so unfriendly

Do you know which trains would be free? How can I find them?

It's easy : there is the hourly reservation-free RE from Lugano. Take any train to there but please note that due to the Gotthard Base Tunnel being closed (freight incident) the journey will take an hour longer as the train takes the slower but beautiful old railway.

For example from Basel :

- IC Basel SBB - Lugano 13:03 - 16:50

- RE Lugano - Milano Centrale 17:02 - 18:17

Or you could take the Lötschberg route :

- EC Basel SBB - Milano Centrale 12:28 - 16:40 11€ mandatory reservation

No booking fees on tickets.oebb.at : add Interrail as a discount and select one-way tickets. It's pretty full though so you'll probably not sit together (seat map checked on trenitalia.com).

If you're coming from Frankfurt I'd recommend this itinerary :

- ICE Frankfurt (Main) Süd - Basel SBB 08:40 - 11:47

- margin for the usual ICE delays + lunch break

- IC Basel SBB - Lugano 13:03 - 16:50

- RE Lugano - Milano Centrale 17:02 - 18:17

Fully free and a scenic route included :)

Thank you -  guess I’ll do so - only change in Lugano seems a little bit risky… there is another EC later after this RE. Is in EC always reservation mandatory? 
I still don’t understand where I can find it out quickly which trains are available without aditional  reservation … 
How did you get so experienced ;-) 

Changes in Switzerland are not risky : 3 min connections are not unusual. And if whatever happens the RE to Milan runs hourly.

EC trains require seat reservations in Italy yes.

You can use a good planner such as bahn.com or DB Navigator app, it works all across Europe. Rail Planner app (which you'll need to use unless you have paper passes) also indicates trains with mandatory reservations. It is also possible to filter connections without.

Thank you,  yes : Wer have the app.  Now watched some YouTube reports how of worked for others.  

Used it last time 2018 but paper version. 

Quite nervous this time.  But I hope it will work out well... 

Second child bis must fly after us in some days as he caught a famous disease just now