I'm not quite sure what you are trying to say, but it doesn't sound quite right to me.
Silkie x normal feathers gives F1 birds with normal feathers.
For any later generations (F2, F3, etc), if at least one parent has normal feathers, you should get some chicks with normal feathers. 50% or more of chicks will have normal feathers in each generation that has a normal-feathered parent, even if the other parent is a pure silkie.
I cannot say whether she has any Silkie or not, but I agree she probably has plenty of non-Silkie ancestors as well. I suspect the crest may have come from a Silkie ancestor, given that she is a bantam and not many other bantam breeds have crests on their heads.