Atreus came with Lance for a little while, though he was like "really" at Margo's offering for entrance, and probably jokingly tried to do it to his own self cause he didn't want to do anything in honor of his uncle π They didn't partake in anything dirty in public but he probably got some magical pot for Lance, or at the very least alcohol. And I think they did take over a private cabana for a while. otherwise he's happy to mingle despite originally being like "Lance that's the orgy party".
And Guillermo came with Nandor, but he was very π about everything and I can't promise he was a good party-goer.