The success of Dannijo, the luxury accessories line created by sisters ­Danielle Snyder and Jodie Snyder Morel, is as much due to the fine art of balance as to the fine art of the pieces themselves. There’s the alchemy of the siblings’ sensibility—“Jodie is more classic/sophisticated, while I’m more rock ’n’ roll and bohemian,” explains Snyder, who, at 30, is three years younger—and the fusion of a brand that is unapologetically exotic but marketed as worn by the girl you wish lived next door.The sisters began making jewelry crafted from wire with their cardiologist father’s medical tools while they were growing up in Florida. After a college internship in Kenya, Snyder cofounded the nonprofit LWALA (Live With a Lifelong Ambition), which raises money for grassroots initiatives in Africa. A year later, the two sisters—by now living in New York City and working in th