Her on-show sister Sara, much like Oliver Queen, let her believe for years that she had actually died in a boating accident, and this after the pair had an affair while Oliver was dating Laurel. Sara did eventually come back into her life, and the two sisters managed to patch up their differences and go back to having as good a relationship as you can with a sibling who spends most of her time running around with a bunch of assassins. In real life, Cassidy has two half-sisters - Jenna and Jaime - and says she would not be so forgiving if they had done that to her: If someone did to me what Sara did to Laurel, I would certainly not be open to having them back in my life!