Samuel Church
Samuel is there, invited as a HP dreamer, and attends with Tallulah! They're dressed as Wendy and Peter Pan. (Yes, they pose like that for at least one picture.) He has a good sense of rhythm, of course, so he doesn't mind dancing (with Tallulah, or Abby or Dottie- not to exclude Tessa per se, but he doesn't know her as well at this point?). He also probably slightly overindulges on pumpkin-flavored treats. Sorry. Once it's revealed to be a wedding, he probably has a moment of, "You can do that?" before just going along with the new cause for celebration.