Why wouldn't you breed the babies to the parents though? You'd be getting much better odds that way.
As for the percentages, when you see an animal that looks 'normal' you know for a fact that it is not a pied, axanthic, axanthic pied, axanthic het pied, or pied het axanthic. So all that remains is double het axathic/pied, het axanthic, het pied, and a normal. So you would basically call anything that looks normal 66% het pied/axanthic.