The only thing Gamebryo was the renderer, which has been stripped and recoded. Check the box, no Gamebryo logo.
You don't really believe that, do you?
It's pretty simple. Buy the license of Gamebryo engine before/during it went bankrupt, change the name to Creation, done.
Last I check, Crytek UK and Free Radical Design are literally the same, except the name and perhaps a few minor modifications.