Arrange to meet with some other parents that you trust to talk over good rules and consequences  that make sense for the ages of your children.  Have a “rule party” (instead of a “pool party”).

Each person can bring a family rule that is a challenge for them and everyone can give ideas for how to clearly state the expectation in a way to be good for the age of the child in mind.  Then, the group can brainstorm what type of consequence would make sense. Lastly, you could discuss ways to help parents stick to the rule and the consequence and not look the other way. 

Remember, you are in charge of your family. All the ideas you hear are for you to evaluate and make the final choices about what you think will work for your family. Announce this as one of the party rules at the very beginning.