This Sunset Park family is growing by leaps and bounds! Lindsay and Dane Demchak were all set to throw a birthday party Saturday for their son Omri, who was born Feb. 29, 2016, the last Leap Year. But that soiree was put on hold when the 31-year-old stay-at-home mom unexpectedly gave birth Saturday morning, four days early, to a 7-pound, 2-ounce baby girl at Coney Island Hospital in Brooklyn. “We’re the double Leap Year family!” a beaming Lindsay Demchak boasted from her hospital bed as she cradled a swaddled Scout on her right arm. “We don’t believe in superstition. We...