Linking park tickets to app

[disny_luvr]

I just purchased our tickets to Disneyland for next summer through Undercover Tourist. Should I link the tickets to the Disneyland app now or wait until closer to our travel dates? I guess my worry is if we can't go for some reason and I need to return them, that I can't do that if they are already linked on the app. Does anyone know if that is the case? Also, should everyone in my travel party download the Disneyland app and link their ticket or can I add them all to my Disneyland app?

Thank you!