To actually produce a homozygous recessive (the visual morph) both parents need to have the mutation.
I just hatched my first pieds from a 10 year project starting with 50% chance het males to normals. It helps that even though pied is considered a recessive morph it has co-dominant tendencies with markers seen in some hets. I kept back the 25% chance het girls with the markers and bred them to an unrelated markered possible het male. Shouldn't have taken so long but worth every year to see them finally hatch last week. Interesting that two well markered now proven hets produced all (3) high white pieds. Makes me wonder if the hets that don't show would be more likely to produce low white piebalds.