The Sunshine Girls by Molly Fader

When Clara's and Abbie's mother BettyKay dies, they are united in grief. The sisters felt loved by both their parents and had a happy childhood growing up in Iowa. When movie star Kitty Devereaux shows up at BettyKay's funeral, Clara and Abbie are confused and have lots of questions, especially about how Kitty knew their mother. The Sunshine Girls follows the story of Kitty and BettyKay meeting in nursing school in 1967 and follows their friendship over the years. This storyline alternates with the contemporary story, mainly dealing with a secret that BettyKay revealed to Clara before she passed away that threatens to upend all the characters' lives. The book is notable for being set during the 1960s-1980s time period, which is uncommon in historical fiction.