Up until I was 6 I slept with my grans petticoat/under skirt. It had to be a certain brand too lol. She used to be in the kitchen and I'd pull it off her because it felt so nice and silky. I think my mum ended up just buying me my own.
Sorry it's a bit off topic but just wanted to say that she'll grow out of it! I'm 26 now and go to sleep all on my own