Sorry for my ignorance but I’m knew to the mobile app version of Eurail. I made a reservation online with OBB for a segment from Florence to Milan--my wife and I have a first class railpass (10 days in 2 months). The OBB price for a seat reservation was something like 20 Euros--but it asked if I wanted to upgrade to 1st class for an extra 4 euros, so I clicked it. How does DB or OBB of SBB know what class my pass is good for? Many thanks for any answers,
Scott