If you want splash silkies you will need offspring from a blue x blue, blue x splash or splash x splash.
blue x blue = 25% black, 50% blue, 25% splash
blue x splash = 50% blue, 50% splash
splash x splash = 50% splash
Pure splash breedings over time tend to wash out the "splashing".
As for breeding to white, white is a wild card. The white gene is an off switch preventing colors and patterns from showing. That means a white could carry just about anything genetically and there is no way to be sure what color the resulting offspring will be.