my brother had his 18th recently and we registered the party with the police, we handed arm bands to those who were invited so anyone without an arm band was asked to leave was also easy for family members who didnt know his friends to spot the ones not invited, the ones that were over 18 and invited had a different colour band again so we k=knew who was legally able to drink etc,
the party went off really well and there was no need to call the cops as it was known that only invited people could come and they had to hand ob=ver their invite to get their band....if you lost your band and asked to leave then that was their tuff luck


GL with it all