I always call the girls baby. Even though I know they are way past the baby stage, I constantly tell them "You'll always be my baby."
Recently the blond twin was in the minivan with me after we dropped the brunette twin at horse camp when she said, "You know I'd like to be your dolly sometimes. You always call Alyssa your dolly but we're your babies and we should be your dollies too."
Wow! Talk about an out-of-the-blue topic.
I replied, "Yes. I do call Alyssa dolly. I've called her that since she was born. I once called you dolly and you got mad. You told me that Alyssa was my dolly and you were my baby."
She thought about it for a moment before letting me know she wants to be my dolly too. So we compromised. For now I call her and her twin babydoll. She flashes this amazing, whole face smile when I call her babydoll. It's nice to be able to make her so happy with a single word.