I dont think she stole her appearance since they still knew who was who. My guess is she somehow altered their memories so that all the love they felt for alyssa would be directed towards her and all the hate would be directed towards alyssa. Thats probably y theyre reacting the way they r when they suddenly remember her
I think she was being harrassed but it didnt particularly show it. thats y she made the comment when she saw the tea that she didnt think water was provided since it wasnt being sent to her room and then the other siblings (aside from the oldest who was just ignoring her) were making the rude disgusted remarks to her
The dream confuse me did she steal her sister apparence also was she a demon or did she contract a demon