I vent sexed my Silkie and she's fine.Vent sexing is not recommended for most people to try. I just wait to see what they are. It is kind of fun to wait and see.
Yellow legs would NOT be on a Black star. I have one and she's ALWAYS had black legs and feet.pink soles versus white soles on the feet. Yellow legs and feet would be a black star or something similar.
I think my Black Australorp's LEGS were black when she was younger and her feet were pink/yellow/grey.