Bless you guy!
Sounds like it wasn't just the bed that turned into a twin, but your daughter as well 😬
Not sure if you're Christian, but my best suggestion is to ask God for the best solution. He'd give you ideas that are specific to your case.
I've heard lots of different suggestions when my sister-in-law asked a similar question, but half of the suggestions were totally wrong for their situation. I remember somethig about removing all the toys from the room, some might have been to leave their favorite toy with them etc. So, kinda all over the place.