Thanks HiroMyHero and ScrapYap!! I was able to find the place to link the magicbands last night, but I wasn't sure if they would automatically link to me or it would give me a screen to pick who to link them to. With your encouragement (Hiro), I was brave enough to get to that next screen and got them all linked successfully. I appreciate you talking me down from the ledge.
We had a successful day using our phantom bands at MK. We already had FPs for Mine Train, Space Mountain and Splash Mountain with our regular bands and were able to schedule Haunted Mansion, Big Thunder Mountain, and Jungle Cruise for SDFPs. It was so easy, thanks to all of the help in this and ScrapYap's thread.
Looking forward to trying them out at Epcot tomorrow!