Improving Fertility in Blue Gouldians

[Paul's Amazing Birds]

Just looking for some advice on improving fertility in Blue Gouldians.
My young bonded pair wasted a few weeks sitting together on their first clutch of 4 infertile eggs. Two eggs landed on the floor before they discovered the next boxes. They have plenty of nest material and the privacy of a large quarantine flight.

Female is blue and male is split to blue. Diet is vitamin-enriched finch plus egg food plus veggies. Maybe they're just to young to understand the courtship/mating thing?

I have about 16 others out in the main flight (none blue) that are singing and dancing all over the place.

I have several nest boxes in the quarantine flight so I'm wondering if I should I add an experienced pair to the blue flight or keep it going as a separate breeder cage?
What do you get when you cross a GB with a BB?
Any changes in diet to spark things up a bit?
Increase the egg ratio maybe?

Thanks,
Paul

[ac12]

Some times they get down to mating immediately after I set them up in a breeding cage, other times not. I currently have a pair that has been together for probably 3 months. They mated last year, but this year, nothing...so far.

I've seen where adding a different food sometimes helps. But it looks like you have that covered with that buffet table.