Gouldian split to blue and greenback?

[goldfinchowl]

I purchased 4 young gouldian males.
Not sure if will breed later.

But if i were to decide to try breed them?
What age 1 yr or 2 yr to start for Gouldian?

Their parents are blue back fathers and yellow back mothers

Since greenback gouldian r way less costly to buy, what would be the color if I got 4 greenback females?
Could any babies still be blue back?

If got 1 expensive gouldian female should I let the males choose or pair in separate cage?

Just considering for the future.

I would probably just end up keeping the babies if one can keep them in same cage with parents when they fledged?
If they all remain together in same cage, would they have to be even numbers to pair up and even ratio of males to females once all babies became adults?