The Broadway Musical opens April 15 at Children's Theatre Company in Minnesota, and Collins joins the cast in May.

Disney is bringing out the big guns ... as Ryder's sister Honeymaren and Ciarán Hinds as Rock Trolls leader Pabbie. After flashbacks in Frozen 2, we could also see more of Evan Rachel Wood ...

How do you reimagine a wintry Disney wonderland while staying true ... particularly for the "hidden folk," portrayed as rock trolls in the animated film. Those characters are used as a framework ...