Blue Orpingtons - Page 7
I am not an expert either but I do know that a BBS black would have a 1-blue gene trait that may show up. Either way as long as you breed the off spring back to mottles I would think it would breed back out. I know several people that use a chicken color calculator on some website to come up with info on their projects. I have never looked for it or used it but May help if you find it.