“I LET MY SISTER-IN-LAW ENJOY MY POOL FOR YEARS. WHEN I ASKED TO BORROW HER TENT, SHE LAUGHED AND SAID, ‘GET YOUR OWN.’ DAYS LATER, MY POOL WAS RUINED—BUT MY NEXT MOVE STUNNED EVERYONE.” My name is Alisa, and for months I was the family doormat. For four summers straight, my backyard pool had been Cassidy’s playground. Every weekend she’d show up with her kids, their friends, snacks, and an attitude like she owned the place. “It’s family,” my husband David would shrug, as if that excused everyth