A black cannot have "some splash." It would be either splash or blue if so. A "black" can actually be a very dark blue.
IFF the black carries a hidden copy of lavender and mottle, you could have some porcelain offspring. Iff lavender, lavender, iff mottle, mottle. But unless you know the breeding of the black carries those hidden genes, don't expect or anticipate it.
Since you got a lavender and a blue offspring, chances are that either the black is a dark blue or it carries lavender or both. What is the difference that makes you say one is a dark lavender and the other a light blue? Can you post photos?