I read the novel but I kinda forgot how it goes.But her sister will try and flirt with Vincent and stuff like that. And there at some point in the novel where Ethan arrives at the mansion and he remembers her and she tell him to be quiet bc Vincent wasn't looking for her and she described her sister but Vincent start getting suspicious but there an moment in the novel that was soo frustrating but thankful Vincent was able to remember. So basically Paula sister claims she's "Puala" bc Paula has being having nightmares with everything that happened in the past and she like sleep talks and her sister toke advantage of that. So when someone from the old estate who works in a flower shop remembers Paula they scream her name and like shhh bc she doesn't want Vincent to know it's here bc she think she's ugly. So I think she yells Paula and Vincent was there and that's when her sister claims she was Paula and hugged Vincent but she's schoked and so they take her away so he can talk to her but he's not fully convinced. But there a point in the novel where Ann is reading to the young master and that's when Vicwnt knows it's her. Sorry if it's all over the place