This explanation uses Dr. Alesandro D'Angieri's The Colored Atlas of Lovebirds page 63 for normal and mutant alleles.
Large letters refer to dominate alleles, lower case for recessive alleles.
I have underlined all of the birds that have at least one allele mutated. The offspring are labeled in percentages of total offspring given hypothetical unlimited clutches. A Yy will only carry the mutation but not display it. In each of these Dutch Blue mutation samples, it does not matter if the genetics of the father or mother are switched. In this way you can begin to figure out the genetics of the parents.