I can empathize with it being difficult to turn kids away...we have been living in our new house on a cul de sac for a year now and there are a lot of kids! It's great for my kids to always have people to play with but difficult when you have 13 kids in your back yard, and you would like to keep it at a minimum but it's hard to say no to some neighbour kids and not others. (FYI- they are never allowed over when the daycare kids are here). It sounds like you're doing a good job and it's working! You actually might not have to talk to their twit mom if you keep up being firm and having firm behaviour expectations. Listen/behave or go home and follow through every single time. Period. They will either get it and change their tune, or they will stop coming around!