My daughter is 15 months old. The pedi said to go ahead and switch her from the sippy to an open cup. She hasn't used a bottle since about 11 months. How do I start that transition? She nurses at home, so we rarely give her a cup. She uses the sippy at daycare. I feel strongly about giving her organic cow and soymilk, so we bring our own sippys. When I offer her an open cup, she'll drink out of it, but she won't hold it herself. If I put a cup with a small amount of water on her tray, she'll pick it up and pour it out. Thanks.