Tried to put a picture of a breeding scheme but can not make it big enough to read. click on the scheme and you can read it as a photo. You can also make it larger by zooming in on your web page in photo mode.
With only 4 birds to breed, (as you said) you have a limited gene pool to work with. What characteristics are not found in the birds that you want to improve?
If I was in your shoes, I would do some crossing between the birds and see if I could improve a characteristic. When you do your...