Maybe it would help her to read stories from the children of poly parents, in their own words. I dont have time to dig up links right now, but I've seen them before and none reported being scarred, even if they said that they didn't think poly was right for them. There's even a study that was done of poly families by a woman whose name I'm not remembering that found the same thing. You can probably find it with some googling. Sorry you're going through this!
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.