I figured Sonoran would say this but I might as well go ahead.
Silkie Feathering is a recessive trait. When you breed a silkie feathered bird to a normal feathered bird, the offspring are heterozygous for each trait. For example, S = normal/s = silkie. Which would make the offspring Ss. In order to get a Silke feathered Long-tail Sultan or w/e it is, you would need to breed two of these heterozygous birds to have a chance at getting a bird with Silkie feathers. Probabilities: 25% normal feathered, 50% Heterozygous, 25% Silkie. It is not preferred to mate brother to sister. Mother to son or Father to daughter is good. So if you would like to make your chances greater, you could mate the Silkie feathered parent to the heterozygous offspring, giving you a 50% Heterozygous and 50% Silkie feathered.
Hope that made sense.
Also, you would have to find a way to breed OUT the black skin and five toes... unless that is a characteristic you would like. But Sultans also have 5 toes so that may be something you'd like to keep since, really, you are making a different variety of Sultan.