I have seen there are discounts available in Switzerland if you have an eurail pass for travelling between Interlaken - Grindelwald/lauterbrunnen. The discount is like 25 percent and is applicable to some cable cars as well. To get that benefit if I buy the eurail pass do I have to add that pass somehow to the sbb app? Or if not to avail the discount I would have to just this pass to the ticket counter? Also do i need to activate the eurail pass on that day?