We are traveling from Frieburg (Breisgau), Germany to Murren in September. We are using German Railpasses in Germany (most of our trip is in Germany). I understand that these passes are only good to Basel Bad Bf, but the trains to Murren seem to depart from Basel SBB. Do we stop at Basel Bad and purchase a transfer to Basel SBB or can we just purchase Basel Bad to Murren tickets from the sbb.ch site? How have other been doing this itinerary?
Buy a ticket from Basel Badischer Bahnhof to Mürren. Yes you can stay on the train and use two different tickets.
The IC and ICE trains from Freiburg im Breisgau to Basel all stop at Basel Badischer Bahnhof but continue to Basel SBB.
Some terminate there but many continue to Swiss destinations (Zürich or Interlaken), after changing crews.
For example: Freiburg (Breisgau) Hbf dep 11:01 ICE 275, Interlaken Ost arr 13:57, no changes!
I suggest you do a search on the SBB or DB website ( http://www.sbb.ch/en/home.html or https://www.bahn.com/en/view/index.shtml ) for Freiburg (Breisgau) to Mürren for the desired date and time. This will tell you where to change trains.