Karen:
You should be able to link the ParkHopper tickets you purchased through your union to your MagicBands through the
My Disney Experience link on
www.disneyworld.com if they are one of Disney's current admission cards. Otherwise, you'll need to bring them with you to the park. If they are one of the current admission cards, you can link these tickets to your MagicBands under Plan and Manage/My Reservation. There, you can type in the ticket number into the indicated fields to link the tickets. Once linked, you do not have to carry your tickets with you. For my trip last weekend, I linked my Armed Forces Salute ticket (which was one of Disney's current hard admission cards, not a paper ticket) beforehand at home.
Once your tickets are assigned to your MagicBand, you can confirm by clicking on the 'MagicBands and Cards' link under 'My Account'.
Unfortunately, you cannot purchase the Disney Dining Plan if you did not purchase your tickets from Disney as a part of your vacation package and room. However, you can still make dining reservations and those will be linked to your MagicBand.
Wishing y'all a magical vacation!
Whitney