i mean the ball is to introduce the secret daughter that was never shown and noone even knew existed, so its pretty easy to assume that she is posing like the marquis daughter, why do this? no fcking idea, coz the plan was for her to ''sleep''
umh...maybe she sealed her mind ( and by doing this sealed the memories of everyone of her)and left her noble daughter persona in control of her body, that way her mind would be''sleeping'', ill be sure if she recognizes him, anyways thks for the chapter