I actually tend to be the opposite and somewhat leave the parents out of it in the sense that 95% of the time they are the reason things are the way they are. I work strictly on the child and my expectations for behaviour in my house. If she then learns to carry it over to home great and if not as long as my days go better and I know that given the need she can behave properly such as down the road in school then I have done my job. At 3.5 she would be read the riot act and told what behaviour she is expected to show etc. When all that fails then fine parents are told to take their kid and go elsewhere cause I have tried and am done. Surprisingly when you call a child out it is amazing how often they turn around and cooperate. When they cry to parents at drop off or pickup that is when you can start to work on the parents by dealing with the child in front of them - teaching them parenting skills. Remind the child of what is expected at your house - my classic line of I don't care what behaviour you are allowed to use at home but while you are in my house you will act like a proper girl with social graces or something to that effect - stern but not mean, to the point and in your face for the parents to get the oops we better do something too hopefully. And as I said if they get miffed and up and leave oh well we will go on with our calm fun day knowing I at least planted seeds of hope for them.