On her special day this summer, 6-year-old Sophia Waldenberg woke up to balloons in her room and a happy song playing on the stereo. She picnicked in the park, rode a carousel, ate ice cream and even got to cruise the aisles of a toy store for a present. "It's as big as a birthday," her mom, Carol Waldenberg, said of Sophia's adoption day. A similar celebration occurs in November every year, to mark the day when Sophia's little sister, Olivia, 3, joined the family.