Lexi - her real name is Alexa - was born in the late '80s. After Isabella was born, Vivian and her husband Diego said they could only afford to take care of one child, so Lexi was adopted by the Caxtons, where she spent her last decade. One day, Isabella and Lexi happened to meet at the mall. They both felt like they knew each other. So Isabella scoured ancestry.com until she had her answer: Lexi was her sister.