May I humbly suggest that, while you might think you know these young adults, and think you can predict what they will or won’t do, you really don’t. So if you are comfortable with the possible legal consequences of serving under age adults in your home, go ahead. Just do it with your eyes wide open, and don’t fool yourself into thinking that you * know* they won’t sneak out, or get sloppy drunk, or end up in the ER after you served them alcohol.
I could bore you with a tale of spending a long day and evening in the ER with a young adult friend of my kid, who, as it turns out, has one heck of a problem with alcohol. I did not serve anyone anything, but she brought her own, had her own little pre-gaming party at my house, continued that while standing in line for a concert they all were attending, and was carted off to the ER once it all hit her… Before the band even started playing. (nobody else in the group was drinking with her.)
That was one heck of a fun long distance conversation I had with her mom while waiting for her daughter to sober up enough to be released from the ER. Thank goodness no one in our house, including my daughter, provided her with any of the booze. She brought her own, and hid it. Just think about what a different conversation it would have been with her mom, with the ER personnel, and perhaps with law enforcement or a lawyer or two, if I had started it all off by serving some champagne at my house to people I knew weren’t of legal age.
Just something to think about.