Ok, preliminary plan:
Stunt: These two think they have a poor little Baroness cornered. But they are wrong. They are rank amateurs compared to the vipers in the royal court. "Well of course I know most of what happened in the Middle East, Countess." Your tone is sweet, the venom in it subtle. "My brother Julius often wrote to me praising Princess Cornelia's accomplishments on the battlefield, before he made the ultimate sacrifice for Britannia." A note of pride, of patriotism. YOu see some of the nobles in the peanut gallery raise their glasses in approval. "It's only natural that I would wish to know more about the woman he idolized, but as much of a miracle as it would be to hear from him again he can hardly tell me more from the grave." You say with a hint of sadness, lowering their guards before the metaphorical knife deftly goes in. "But I'd suppose your families go to quite some lengths to make sure you never have worry about such things, don't they?" You twist the knife, opening a wound of horrid truths. They're parasites married to parasites. They've accomplished nothing. That they are guilty of the worst sin a Britannian noble could be perceived of committing. Being weak. That a mere Baroness would dare make such an accusation without fear only makes it more apparent as truth.
For Charms, I would use WTTLD to give Lucinda an auditory hallucination to make it seem like people in the crowd are quietly mocking her behind her back to put her on the backfoot, and use a bit of the Ebon Dragon's Excellency to give us a few extra dice. Maybe two or three.
Thoughts?