We did it a couple of different ways on our trip. Initially, I was the keeper of the LL redemptions. I would take my phone up to the redemption stand and scan each one in for all 4 of us. I would then let my kids take turns scanning us in. On the final day when the kids went off on their own, I had my oldest download the app and sign in on my account. I showed her how to book the LL for just the two of them. They then went off and had no issues scanning in without us.
You can also use the physical tickets but we've got 2-4 of us with ADHD (wife and I are undiagnosed) so that's 4 small items any of us could lose pretty easily.
If Magic Bands were an option, I would've been all over them. I love that part of WDW as it's one less thing to worry about, outside of actually making sure everyone has theirs when we walk out the hotel room door.