@Lori3686
I do not have in my house rules but you have to validate your specific state laws . A bar or a store can not serve alcohol under 21 years of age, but in some states a minor at a certain age if supervised by whoever is the custodial adult in a private setting within limits iis not a prosecutable charge. I rent your house and I give my 18 year old a beer is seen differently then I rent your house so my 18 year old throws a party with a group of minors without the custodian giving approval or supervising.
I have seen some hosts to prevent the underage parties require all guests must be 21.
What actual issue did you have then maybe that could be better answered.