Speak for yourself

--- Thanks to Duskwolf for the idea---

He stops Dietrich and turns the situation around, using his mother’s state of undress to his advantage.

You place your hand on Sir Dietrich’s shoulder, stopping him from standing up, as you stand up in his stead. “My dear followed members of this joyful wedding; I do not understand where this very honorable man concluded that I provided this fabulous gown. But I am more than honored that this wonderful bride had chosen to wear a dress that does not hide the child her King’s placed in her womb on the day of her celebration. Such an act shows true devotion to duty and devotion to her King. A devotion that I am sure that she will place into her new marriage.”

Hearing your words, Sir Dietrich stands up and uses his silver tongue to proclaim, “Such a devoted display deserves recognition. Three cheers for the mother of our King, our king’s concubine, and the future Lady of this land. HIP! HIP!”.

The room goes silent as the who room looks at each other, questioning which one would be brave enough to say anything until one noble awkwardly says “Hooray?”

Sir Dietrich, understanding what he is supposed to do, repeats, “HIP! HIP!”

This time, the room breaks out in a boisterous cheer as of the King’s supporters, yell “HOORAY!”

The third time that Sir Dietrich shouts, “HIP! HIP!”, the entire room joined in a thunderous “HOORAY!”

As the cheers die down, you address the shocked Lady Dietrich, “I love you, Dearest Mother. Thank you for carrying my child, and should you desire it, I hope it will be the first of our many children. At least until the day you decide to retire to spend your twilight years with a man who loves you.”

From his hiding place behind the curtain near the entrance, the Arch Duke looks in horror as his plan comes crashing down right in front of his very eyes. He had schemed to make you the bad guy, but the whole situation had been flipped upside down and everyone in the room end up rooting for you.