In Welcome to Storybrooke, Regina said to Gold that Mary Margaret tricked her into killing her own mohter.
And In the Miller's Daughter, Cora dies after Regina returns her heart. Technically Regina is one of Cora's killers. Mary Margaret cursed the heart, but Cora would only die if her heart was on her chest. So why isn't Regina's name in the list of death in Cora's death section togheter with Mary Margaret?