The two in your pic look like hens, im having the same trouble sexing my silkies. I have one that im almost 100% sure is a roo. His "hair-do" on top is larger and is starting to slick backwards down the back of his neck. The hens usually have more of just a poof on top (from what I've heard). If you upload a pic with a closer look at their heads you can probably get pretty good idea. By like the others said, sometimes you just have to wait for them to lay. I've had what I thought was a hen start crowing and vice versa lol. Good luck!