I will only hrow a party if the departure is on a positive note.... new baby, going to "big kid" school. I do not throw parties for children that have been terminated.

As for how the other children react when one leaves... Most of my kids dont even notice. I have had serveral children come and go in my past year (due to mat leaves etc) and I could count on one hand the amount of times that one of the departed children were mentioned.