Jul 14, 2016 - 12:26 PM
After reading your posts I'm not 100% sure which sections you're aiming at. Do you mean Zurich-Milan, Zurich-Chur and a return trip Chur-St. Moritz and back? Here are some options:
- the Swiss Half Fare Card mentioned by Arno: valid for a 50% discounted travel on all journeys within Switzerland. You'd still need an additional ticket from Milan to the Swiss-Italian border. Depending on the connection you pick, a Swiss Half Fare Card will be valid from Chiasso or Domodossola;
- a Swiss Travel Pass, allowing free traveling throughout the country. Again, you'd need an additional ticket from Milan to Chiasso or Domodossola.
The pages I linked to provide up to date and correct information about both passes, including a detailed validity map, purchase options and further details. Arno provided you with the link to calculate your options. Unfortunately that's the only way to tell for sure which pass suits your needs best.
There are Eurail passes covering the leg from Milan to Chiasso/Domodossola too, but those are valid for several European countries and too expensive for the itinerary you've outlined here.