Since lavender is recessive, unless you breed to another lavender bird it acts the same as black genetically. So in essance you'd be breeding a black bird to a gold laced bird. I believe that would give you black birds with incomplete lacing.
I've not heard of lavender cochins though. Are you...
I've been doing the mixed breed thing for too long, I think .
First is a pen of blue/splash blue eggers. Father was a splash Ameraucana, the hens were random project blue or green eggers, mostly blue, black or black barred. And the little silkie broody momma
Blue egger blue sex links...