When I came on the scene, and asked Sparkle to explain, it was all, "It's HIS fault," (pointing to Daddy) "Because HE grabbed my HAND and made me leave the room!" She waxed eloquent on how she didn't like it, and it wasn't her decision, and how her feelings were hurt, and she was mad, mad, mad. Daddy bore the accusations with patience.
I asked Sparkle, "And what did YOU do so that Daddy had to remove you from your big brother's room?" Sparkle opened her mouth, took a breath, and then wouldn't look at anyone. She launched into a repetition of her griefs. I repeated my question, and my darling husband explained. Sparkle started making arguing noises, trying to play the youngest daughter denied access to whatever she wants in the name of peace game.
I said to Sparkle, "You went in and ripped apart something that was important to Dino. How would YOU feel if DINO came out and ripped up something important to you, like your Power Puff Girls?" I had meant to make an allegory, a comparison. I got Vesuvius.
Sparkle freaked out, thinking I'd just given permission for Dino to shred her favorite dolls. I explained to the wall of tears that we weren't going to rip apart her dolls, but that she ought to remember this feeling, because THIS is how she made DINO feel when she messed up HIS stuff. Sobbing, Sparkle got into her winter outdoor clothes, put her girls in her backpack, and declared she was leaving. My husband and I assisted in getting her into her snowpants and boots, and she went outside, wailing, and spent about twenty minutes outside stomping in circles in tears.
I turned to my husband and said, "There isn't any situation that I can't make worse."
He responded, "No, I think that helped."
We had a conversation with Dino where he said he felt a bit guilty about being triumphant that Sparkle didn't get her way. I told him that was fine to feel good about having his stuff defended, but warned him that he was not to use threats against the Power Puff Girl Dolls in negotiations with his sister, or....Dino got it. When Sparkle let herself in, Dino hugged her, and she hugged back, and promises were made all around to respect each other's stuff.
I'm still not sure that Sparkle understands it was a comparison, not a threat. I'm not sure how else I could have handled it, but think it was a fairly good outcome despite my being tired, hungry, and achy when I entered the fray.