Hi, I’m planning to book Budapest - Rijeka overnight for this summer. On the ‘night trains’ part of the interrail website this is available, as the Istria express. 

However, using the app I cannot find any journeys with less than 3 changes. I also can’t find another website to book through, and even if I could, I wouldn’t know how to add the pass as a discount. 

Please can someone help? This is to book a night train.