After her parents' divorce, Bea's life became different in many ways. But she can always look back at the list she keeps in her green notebook to remember the things that will stay the same. The first and most important: Mom and Dad will always love Bea, and each other. When Dad tells Bea that he and his boyfriend, Jesse, are getting married, Bea is thrilled. Bea loves Jesse, and when he and Dad get married, she'll finally (finally!) have what she's always wanted—a sister. Even though she's never met Jesse's daughter, Sonia, Bea is sure that they'll be "just like sisters anywhere." As the wedding day approaches, Bea will learn that making a new family brings questions, surprises, and joy.