We will already have a global train pass when we enter Switzerland. Will it work for all the trains in Switzerland?
It is not on all of the trains
Here is the area of validity
https://cdn-doc.myswissalps.com/docs/default-source/rail-network-maps/eurail.pdf?sfvrsn=b9c49bca_36
And here are more details
https://www.myswissalps.com/eurailglobalpass/validity
https://www.ricksteves.com/travel-tips/transportation/trains/global-pass