Hi Tasha! Welcome back to the Disney Parks Moms Panel!
If I understand your question correctly, you've ordered your Theme Park tickets and would like to use them with Magic Bands you already have. Since you can see your tickets in your My Disney Experience account, you should be able to use your existing Magic Bands with them. You can still stop by and pick up your admission cards for backup if you like, but you don't really need them.
If you're staying at a Walt Disney World Resort hotel, you'll likely receive another set of Magic Bands, either in the mail or for pickup at your resort. I've seen it recommended that you de-activate old bands as you receive new ones, but we have about six different sets of bands and have never had issues using them interchangeably (I've been known to match my Magic Band to my outfit).
I hope this answers your question, Tasha. If you need me to clarify, please feel free to stop by again and ask me another question. I love to help!
Have a magical day,
Kathy K.