I think its off a red dimorphic that one but I do have a mix of hens. One of my muling cocks threw quite a few coloured birds so he's getting all the hens next year if he makes it through winter.
If your going to let them free breed in an aviary you won't be able to pair best to best etc when it comes to the showing or colour side of things so just get some nice birds that you like the look of.