Yes, green is always dominant to blue, and if you got all green chicks, that means the father is not split to blue, he is double dominant green, which means all the chicks will be green as well However, because Yu is blue, all chicks will be split to blue.
Yu is greywing and sf dominant pied, sky blue yellow face II. Astro is recessive pied light green. Since you got opaline chicks, he must be split to opaline. All opaline chicks are female. (You've only got one - budgie 3)
Additionally, greywing is recessive to normal, so Astro must be split to greywing as well, since you have greywing chicks.
It's absolutely possible that you get normal chicks since single factor dominant pied only needs one allele of the dominant pied (the other allele can be normal) and recessive pied is, well, recessive, with only one copy of the gene.
Chick #1: Light green normal
Chick #2: Light green greywing
Chick #3: Light green greywing opaline
Chick #4: Light green greywing sf dominant pied
Chick #5: Light green sf dominant pied
All chicks are split for recessive pied and blue. Half the males will be split for opaline (it's impossible to tell which are unless you breed them). All normal chicks are split for greywing.
Hope this helps
Thank you very much for the helpful info! I've read a lot about mutations and genetics, but there's so much info, it's hard to keep it all straight. This is very useful.