I'm not sold on the half sider idea. All the half siders I have seen are split right down the middle. The green patch and one yellow wing makes me think yellow face maybe.
Pretty birds!! Genetics fascinate me. I'm curious about the mutations/splits, etc. I have Tiels as well and have learned quite a bit about them. As far as yours go.. do you know what the parents were or did you figure out the splits based on what type of chicks they had? And also, if neither of those, are there tell signs of what they are split for, similar to Tiels for some splits?
As for Petey I know he is split for cinnamon and ino because I bred his parents. But I didn't know he was going to be split for opaline. Petey's father is lutino so that mutation masks many other mutations like opaline. I'm not sure of Stella's genes though. I bought her from a pet store.