A black-lavender split would look exactly like a black chicken.
Your rooster looks blue.
It is possible for a blue chicken to also carry the lavender gene, but a blue chicken who carries lavender would look exactly the same as a blue chicken who does not carry lavender-- so there is no way to...
Do they have black/blue/splash? A black from such a flock would work.
Or get two blues, breed them, and 1/4 of the chicks should be black.
Most chicken shows care how the bird looks, not what genes it may carry. So showing a black (with lavender ancestry) should not be a problem. If the...