Atreus and Darcy are both there! Atreus was there most of the day to help setup and then enjoyed the party after, he would've invited Dorian. He did go back home to shower and change into something more formal/hot. He was definitely in for axe throwing and putting bets there.
Darcy 100% reused the dress she got with Margo from Valentine's Day because she is on a Limited Budget and a new arrival so. money goes towards sweaters not dresses. But she was super down for partying and dancing and being also weirdly awkward with people who know her better than she knows them. she's always on hand with a dry quip tho. And doesn't say no to invites to dance BUT she ain't the greatest and doesn't care.