This morning, I put fresh batteries in KatyBeth's baby doll (it's the kind that says, "mama", and general baby babbles). This delighted my soon-to-be-three year old, who has been walking around cuddling the doll ever since, proclaiming (as one would expect) that she is the baby doll's mama. Lily is also fascinated with the doll, smiling whenever it babbles, and often reaching for her. In an unsurprising addition to the game of pretend, the baby doll's mama declared Lily to be "the baby doll's big sister".
