I am so sorry to tell you this. I have 6 Buff Orpingtons. I got four 2 years ago (one died at the jaws of a predator) and 3 more last year. This is what my first batch of BO's looked like at exactly 6 weeks old.
Here they are at 7 weeks...
Here they are at 16 weeks!
And here they are today.
There is absolutely
no question that you have all roo's. I'm really sorry, Now if you got these birds from a "breeder", then I can tell you that she is FULLY aware that they are roos as well. I would see if I could take them back and ask her for females if I were you. My hens are hatchery Orpingtons, and they tend to have LARGER crowns than breeder stock. She is not being truthful. It's not fair to you because clearly you can not keep all rooster.
Kelly