Well, "Sister" you have right... The picture is Josefin Ljungman and she plays Jenny in the movie.
But... Have you seen the hole movie? Do you understand Swedish?
This scene is just in the beginning of the movie and it's the character 'Lisa' who starts to blow Bill Skarsgard´s character 'Martin'. Then she went abroad and later on 'Martin' finds 'Jenny' and so on...
And IMDb says that 'Lisa' is played by Therese Andersson.
I can also admit to you that Therese and Josefin are similar to eash other.
#Nils