Are ther any visual clues or persumptions to identify a split to fallow Cockatiel?

I have a pearl male split to cinnamon and I assume-pied (he has a tell-tale yellow spot on the back of his neck).He was paired with pearl WF (split to pied) and had 4 babies, none of them pied. Because of some issues with the hen I had to pair him with another one- a pied pearl this...

The breeder I got him from told me that my boy Genji is a pearl split to pied. His parents are a pied split to pastelface, cinnamon, and pearl (father) and a normal pearl pied (mother). With my (very rudimentary) understanding of genetics, wouldn't all the babies be pied since both the parents...