Hi! I will be buying two navigo easy passes - one for me and one for my daughter. If I download the app on my phone, will I be able to add more tickets to both cards or does the app link to one card only?
From the description of the Bonjour RATP application (or the Ile-de-France Mobilities app, either works, both are official, one is by Paris transit administration, the other by the regional transport authority), it should be possible to recharge multiple Navigo Easy passes with a single telephone. Navigo Easy passes are not personalized to an individual (they're anonymous), so I don't see why the app should have any issues charging multiple passes (in theory!).
If one or both of you have particular Samsung phones, it's possible to purchase & store the tickets directly onto the phone & application without the physical Navigo Easy card. (iPhone is not supported at the moment.)
Only these phones are supported as of May 2023: Samsung Galaxy minimum Android 6.0 : A5 2017, A8, A70, A71, A80, S7/S7 Edge, S8/S8+, S9/S9+, S10/S10+/S10e, S20/S20 Fan Edition/ S20 Fan Edition 5G, S21/S21+/S21 Ultra, Note 8, Note 9, Note 10/10+/10 Lite, Z Flip/Z-Flip 5G, Fold/Z-Fold, Note 20 Ultra, Note 20 5G.