1/2. Correct. You can also bring your old ones in case one of your new ones breaks or you want to color coordinate with your outfits since they'll be exactly the same as your new ones in terms of how they function.
3. Correct
4. Correct (as of now)
You shouldn't have to do anything with creating a new MDE if those prior family bands are currently linked to your MDE and (as of today) should be able to modify them via the app (assuming again, whoever's bands they are has made it so you can view "all" of their plans - not just "shared" plans). If for some reason you can't do this (ie it's a more distant family member you wouldn't want to ask, etc.), you could still use them for SDFP and just make all changes on the kiosk (and snap a pic of them as you went). I have several cards I use that aren't linked to my MDE and since there are no longer any tickets linked to them, I can't add them. But I can still get SDFP and just change at the kiosk. If the bands you have were linked previously and not in your MDE, you can't link them to a new MDE anyway. That's more for people buying new, unlinked MB's.
I'd just keep reading in this subforum as people post if there are any changes.
Excellent...thank you so very much for the detailed repsonse. I will keep reading!
Another question. Last year when I visited WDW, I brought 4 paper tickets for family members with non expiring water park visits. They converted these to green plastic cards when we used them at TL. However, when I went to MDE these cards are not showing up/linked to any current family members on my new ressie. Does that mean I can create another MDE and use them for SDFP+? Or should I add them to my current MDE account with phantom names for SDFP+?
Thanks a lot. I love this stuff!