OOC: Summary for Hannah
Hannah would have been on her very best behavior, though she lacked any of the upper class upbringing to guide her. She was, however, incredibly polite. She likely messed up the etiquette of which fork was used when, but her posture was excellent and she never said a bad thing or a harsh word to anyone and she generally had a smile on her face, even if she thought the entire day was some form of hell. Hannah is on her Best Behavior when she's among the enemy.
She would have asked no questions of Narcissa, and apart from a polite inquiry as to the health of her son, she would have avoided the woman as much as possible. During Free Socializing Time, she probably would have sought out Cho, both to compliment her on her lovely gown and because she probably knew of her due to following Quidditch and being in the DA with her.
She wore this to the formal tea and changed into this for the formal portion of the evening. She was sure to display her engagement ring to anyone who seemed interested, and complimented Alex's excellent taste. Her accessories were chosen to compliment both outfits, though even the stylists wouldn't have been able to convince her to part with the bracelet or locket since both were gifts from her mother.
As an added bonus, her shoes were brand new and incredibly painful, which made the evening awful by the end. She was a little trooper and kept them on to the bitter end, though she cheated and slipped them off during dinner.