MagicBands and ticket pickup

Having not been to WDW for four years (and that's a huge gap for me!) I'm still getting used to the details behind MagicBands, FP+ and the likes. Got a question and wondering if anyone might have been in the same situation and might know the answer.

We'll be staying off-site and have purchased 21-day Ultimate tickets from the Disney website. While we are supposed to pick the physical tickets up from Will Call, we've got the reference numbers already and have plugged these in to My Disney Experience without a problem (just 27 days till we can book our first FastPasses!).

However since then, my in-laws have come back from Florida bearing new MagicBands for us (not currently linked to any account). If I go ahead and add these to MDE, I would have thought that this means the bands would then have our tickets on them and so we wouldn't need to go to Will Call any more - we could just go straight into the park on our first day. Does that sound right, or am I missing something?

Sounds right although I haven't tested it myself!

Yes this should be fine, we did this with our Annual Passes, we didn't need to pickup the actual cards to get in MK, we just picked them up at Will Call at a later date.