Hi. Myself, my husband and 2 children, 10 years and 12 years, will be traveling from Milan to Interlaken on the 17th September. When I go to book tickets it allows me to put in a half fare discount code for the adults. However, it is still charging a ticket price for the two children. I thought children were free if traveling with their parents who hold a Swiss Half Fare Card? Do I need to put a discount code in for the kids too? Thanks