This letter lays down the law that children cannot behave in a certain way in your home.
1234, Main Street
Boston, MA 02123
07 April, 2005
<Recipient Address Goes Here>
After your family's last visit to my home, I realized that I need to be clear about something with you. While your children were here, they <behavior you disapprove of>, which is something I do not allow in my home, as a rule. Therefore, I'm asking that you instruct your children that when they're in my home, they are to abide by my house rules. The same goes for all visitors to my home.
This is a simple lesson in common courtesy that I think it would do the children good to learn. I hope you don't think it rude of me to insist on this, but I think we need to teach children to respect the property and wishes of others, and this is a good opportunity to illustrate that lesson.
encl: <List of enclosed items goes here>