Dear Mrs. Malfoy,
As you may know, I have been given the enviable position of event planner for the Ministry, and I have been asked to help Miss Chang and Mr. Flint with any preparations and arrangements they may need for their wedding. Miss Chang told me that she will be meeting with you today to get your guidance on the wedding, and I would like to request that you allow me to sit in on your meeting, so that I will be able to provide information on venues, suppliers, and other such things to help you in your decisions and help implement any decisions you make.
Yours with the utmost respect,
Astoria Greengrass