The Conditions of Will by Jessa Hastings

London-based Georgia Carter, professional lie detector and body-language savant, has long been estranged from her infuriating, close-minded, wealthy South Carolina family. After a falling-out years ago, the chasm runs deep between the black sheep―Georgia and her gay, alcoholic brother―and their parents and elder siblings. But when their father dies suddenly, Georgia returns to the States for the funeral…where she comes face-to-face with Sam Penny, her brother's AA sponsor.