I bought an Bernese Oberland Pass for the Swiss part of my journey. I will be in Turin and need to know how to buy a ticket to Domomosola. I think the BO pass will cover my trip to Wengen. So my question is, What train to get to take me to the town where the BO pass will kick in.
When is your travel? Give us the dat, as that is very important in this case.
The ticket Torino - Domodossola you can buy on Trenitalia. If you book an EC service from Milan to Domodossola you can just stay on the train till Brig. Than in Brig you must transfer to the RE service that goes via the old route, as the BO pass is not valid on the new route. To find the old route enter "Göppenstein" as a via in the SBB trip planner.
There is a rail closure on the line between Milan and Domodossola beginning early June, so a replacement bus service is needed. However, coming from Turin, you can take a regional train from Turin (calls at both of the main stations, Porta Susa and Porta Nuova) to Novara and change to a regional train to Domodossola. Regional train tickets can be bought at the station as they are unreserved, price is always the same and they don't sell out. Trenitalia is showing 14.60 EUR as the price.
Only issue is that this connection departs rather late, at 11:54 am from Porta Nuova station. That gets you to Domodossola at 3:42 pm, in time to get the 3:58 pm RE 1 from there to Spiez with connections on to Wengen, arriving at 7:11 pm.