Saveria you are a quick learner, perfect your explanation.
I like to admit a liitle genetic.
Quaglia have a different ground-color than Black.
Pure Black should be E/E based on Silver or gold reinforced or not with Ml/Ml (=Melanotic a black-pigment intensifier)
Quaglia should be eb/eb based on silver or gold, black-pigment restricted by Co/Co or CO/co+ and reinforced by Ml/Ml or Ml/ml+.
So indeed a cross between Black X Quaglia should result in unpure Blacks E/eb carrier of Co and Ml.
Now you must continue with this F1.