Sam2 –
I Googled underage drinking in New Jersey and a link came up with all of the laws that included the following sentence:
Exemptions: Any underage person or persons who possesses or consumes alcoholic beverages in connection with religious observance, ceremony or right or consumes or possesses an alcoholic beverage in the presence of and with the permission of the parent , guardian, or relative who has attained the legal age to purchase and consume alcoholic beverages.
So “dina d’malchusa” is not necessarily relevant.
Furthermore, Baloochi’s question is relevant in places outside the US where drinking ages can be significantly younger.
Personally I think there is no reason – in a normal situation – to be serving alcohol to kids, because you gain nothing, and chances are they will abuse it.
As an aside, I think that sentence is supposed to say “ceremony or rite,” not “ceremony or right.” If it’s the way it’s written there’s probably a lot more room in the law to be meikil.