Bridgette Zunino-Denison and Jayann Sepich share a bond that can only be understood by an unfortunate few forced to endure an unspeakable tragedy. Their daughters, Brianna and Katie, never met, but their murders in Reno and New Mexico have linked their mothers for life — and united them in a quest to protect others. “I knew other mothers who had lost their children to accident or illness, but being murdered is different,” Sepich said Wednesday. “Bridgette doesn’t imagine my pain, she knows my name and I know hers.” They are urging Nevada lawmakers to pass Brianna’s Law, a measure that …