Here's the "romance graph" for this game. Arrows are colored based on character: Joanne=red, Kira=green, Thalia=black.
The estimate release date on top is not to be taken too much seriously
Haha poor Arianna. Everyone wants to do dirty things with her
Thalia is in her happy facial expression. Some characters have a "slightly happier" neutral face, while others more "sad" one. Hard to explain, just some minor differences in the facial expressions
By the way, I forgot if this has been asked before, but can you choose which sister to play at start, something like "Seasons of the Wolf", where you pick Althea or Shea? And the other siblings will simply be a part of the story?
No, in this game it's more like "The Sims", you can control any sister at any time. If you want to play with only one, you can, but the game is told in third person.
Was the only possible way, since writing the story from each sister POV would have been nuts