Blue X Blue = 50% Blue, 25% Black, 25% Splash
Blue X Black = 50% Blue, 50% Black
Blue X Splash = 50% Blue, 50% Splash
Black X Black = 100% Black
Splash X Splash = 100% Splash
Splash X Black = 100% Blue
Yes blue to blue and splash to splash and blue to splash make splash.
One note that has not been brought up
You should NOT breed your coppers with blue or splash. True Blues and Splashes are hard to find in Marans.
Breed your Coppers with coppers and your solids with solids.
The good thing about Blue Black and Splash they can all run together BUT the Coppers are a variety and should not be breed with NON copper marans. The Copper will pollute your blues. Keep the NON Coppers pure if they are really pure (should not have any copper/gold leaking ONLY BLUE)