Here is what my chicken chart says, not sure if it is true, but it is worth a shot.
Crest (Silkie) X No Crest = Imperfectly dominate
Dark Shanks X Light Shanks = completely dominate
Extra Toes X Normal = Imperfectly dominate
Feathered Shanks X Normal Shanks = Imperfectly dominate
Silky pigmentation X Normal color = Imperfectly dominate
Walnut Comb X Pea, Rosecomb = Completely dominate
I dont see why you couldnt have a Silkie Cross. I hatched some out this summer and they had a crest, and some had four toes, with no feathered feet, and an assortment of combs, but all did have darker skin. Here is one of my girls.
Silkie X OEGB
Your other guess seems very understandable considering. You may want to check skin color, it should be white if Appenzeller. But, then again you never know what to expect from a hatchery bird. However, if the skin is darker I would think it is a Silkie cross.