Lavender (self blue) is recessive and is not related to blue at all.
Split is a bird carrying 1 recessive gene which doesn't express.
1 All offspring will be black phenotype.
2 All parents and offspring will be black phenotype. 50% carry 1 lavender gene but you cannot tell which ones.
3 50% black and 50% blue phenotype. Blue is a gene that dilutes black. All chicks that get blue gene will be blue.
4 25% of offspring get no blue gene, black phenotype.
50% of offspring get 1 blue gene, blue phenotype.
25% of offspring get 2 blue dilution genes, splash phenotype.