White created blue polish

[Chickalita]

Was wondering if the white crested blue polish is only possibly by breeding other blues or if it’s possible to create through breeding white crested black with white polish. Or would that only make splash

 

[NatJ]

Was wondering if the white crested blue polish is only possibly by breeding other blues

You can breed White Crested Blue to White Crested Black and get some of each in the chicks.

or if it’s possible to create through breeding white crested black with white polish. Or would that only make splash

That breeding will probably not make splash.
It might make paint (white with bits of black, caused by the Dominant White gene that turns black into white)
Splash is caused by two copies of the blue gene, and will absolutely not happen when you cross a white with a white crested black.

If you cross the white with the white crested black, and then breed the offspring back to the white crested black or to each other, there is a chance of getting blue in some of the chicks (if the white was carrying the blue gene, which you will not know unless you try it.)