Dear Family Members,
I've called this meeting because something very disturbing has been happening which we need to discuss.
It has come to my attention that someone in this family has been taking the pens from my desk and not returning them. I'm sure whoever "took them" had a very good reason to "borrow" one of my pens and simply "forgot" to return it because that's the kind of person I am. I like to give people the "benefit of the doubt".