
Her fiance and cousin are probably together and needed her out the way. She seems to know whats going there if she just snuck in to the party. Could have met Edward anytime before this. Scarlets family is grieving it's a perfect time for her to start taking over her life and make it seem like she's comforting them.
Or already knew....
Though she never said anything she never hid it either
He probably had a feeling since the beginning of when they met. Her reactions and words, the look in her eyes resembled her past self