Super saver ticket or pass on Bernina express ??

I don't see any Super Saver Tickets available for the Bernina Express trains on September 15, but the normal price is 32 CHF each way (plus reservation fee, which you already have). But if you are getting Half Fare Cards, that will only be 16 CHF each way, or 32 CHF per person. Since it looks like Saver Day Pass with a Half Fare Card will cost 44 CHF per person when they go on sale in a couple of days, you are better off just buying tickets. 32 CHF is less than 44 CHF.

Thank you Sam, I guess if I can get the 29 CHF price then it kinda makes sense though not a lot of savings. I was able to get 29CHF for glacier express, since I bought right on time 3 pm PST and in 5 minutes it changed to 44 CHF.
So last question is I don't need to buy ticket for my son on Bernina ( only reservation) since we will be having family STS card for him.

Thanks

Yes, he travels with you free with the Family Card.

Hi, a supersaver ticket is for a specific train/route - for example the 8:48 train from St. Moritz to Tirano on Sept 15th. Tickets like this are usually available through the SBB app up to a few days before travel, depending on how busy the train is.
A supersaver day pass is valid for the entire day on any train, bus or boat in Switzerland (with very few exceptions). These are the ones that begin selling 60 days before the travel date and the cheapest ones sell out quickly.