Yup it is a silver sex-link with the Brahmas mom, i dun o bout the NH. Females will be Dads color and males will be Moms color. So if you have a Buff Cochin and a light Brahma Male babies will be black and a little yellow, and females will be pretty much all gold, maybe a black streak or so. But if you have a buff cochin and a buff Brahma, I dont think that is a sex link. What color are your birds? The cochin and brahma?
I am glad you asked this I think my little guy is a cockerel but here he is momma is RIR dad either splash or blue cochin, here is the link to the thread where I posted pictures.