Sorry but it's hard to guess with the color saturation and white balance of those pictures. it's best to take pictures at eye level with the chicks, with them standing, in natural lighting if possible, and a white background. a white towel draped over a box sitting on a table like in this picture for example works pretty good for getting a general ideal of true coloration.
It's likely they have pea combs, because it is usually fairly obvious if they have single combs. Since Brahmas have pea combs unlike Cochins, chances are they are Brahmas.