How did I get Silvers from this Zebra pair?

[Chris103]

I have a pair of Zebras that have totally confused me with their first clutch. The mother Is a Black Face Fawn/Pied and the father Is a normal split to Penguin, silver and pied. How could I get silver chicks from this pair? The male Is the only Zebra I have with Silver genes. Two of their chicks are visual normals one Is a normal pied and the other two are silver. The only silver genes I know of are dominant or recessive so how could I get silvers from this pair? I'm hoping someone can help me figure out how this pair could produce this color. I'll try to take pics of the chicks ASAP. Thanks in advance for any replies!

[Vargur]

If none of the parents are visual isabels then both of the parents must be split for isabel.
(silver)
Zebras can hide genes/mutations, so even though you know they are split for something
there can always be something more they are hiding in their genes!

[Chris103]

Thanks for your reply! It would be almost impossible for the hen to be split Isabel. I have been breeding from the hens line for years with no Isabels popping up.... but it must be the case to explain the color of their chicks. Can't wait for them to fledge and color out!