Hallo Xoaphoickick34
Good day …
You are using a train line that is suffering from its own success. We are unable to say whether the non-reservable cars will have sufficient space. These were intended for the locals who need the trains to go about the local businesses.
Another possibility is by postal bus, from St. Moritz to Lugano, called the Palm Express. From there by train to Como.
Kind regards,
Roland