Sorry for my late response. I really should check my own place more often
That's what director Lynn Shelton said about the characters so far. There are no names given yet though.
[...] Rosemarie DeWitt plays a massage therapist who can’t do her job because she develops a sudden repulsion around the human body, poor dear, so she goes into an identity crisis and journey of the soul. Her brother is played by this incredible actor Josh Pais, and he is a dentist, and they have a very spicy—to say the least—relationship. And he goes into his own journey of self-discovery in another direction that I want to keep mysterious. And they have a sort of tug-of-war over this person in their lives who they both care about very deeply, Josh’s daughter and Rose’s niece, who’s played by Ellen Page. She is in an unhealthily codependent relationship with her father, who relies on her heavily, and it’s clear that she’s kind of sacrificing her own life in service to his. So Rose’s character is really trying to get her out of that situation. That’s the dysfunctional family center. And Scoot McNairy, this wonderful actor who’s about to blow up, is the boyfriend of Rose’s character, and Ellen kind of has a little crush on him. The cast is rounded out by Allison Janney, who plays a mentor and a friend to Rose—and then Ron Livingston is a kind of mystery man: He has just a couple of scenes, but really key scenes, near the end. [...]