Your daughter is having trouble with the change in her life. I suggest you use emotional coaching to name and welcome all of her upset - for instance, when she tells you to "take the baby back" you can say something like, "You're mad at the baby taking Mommy's time. You want it to be like it was before, just you and me." By showing her you understand her feelings, she will feel calmer. By not arguing with her or trying to talk her out of her feelings, she will actually heal faster. In addition, I suggest you consult a Bach Flower Practitioner. This harmless vibration form of treatment can help a child adjust more easily to change and help heal separation anxiety, sleep disturbance and other symptoms of intense upset.  Sarah Chana