Utensils

Question

If you are a non-kosher affair and they give you a kosher meal with plastic utensils, you said that you can still use the regular plates since we assume that they have not been used with non-kosher in the last day. Let's say I am arranging the dinner, for Jews and non-Jews, and for the Jews I am getting kosher meals. Can these kosher meals be served with the regular caterer's plates, or since I am organizing it, do I have an obligation to arrange for kosher plates? In general, is it only if I own the plates that they must be kashered?