You can also get them Downtown Disney at the pin store. Make sure you have the tickets with you as they won't sell the bands without linking the tickets for you right that minute. I did it just a couple of weeks ago.
If they have linked their tickets to My Disney experience, they can book Fp+ 30 days before each day of ticket use. Do they understand they do not need MagicBands at all? Their tickets will be tapped at Fp+ tapstiles and at entrance tapstiles.