Well now, a most unusual pairing, but I think I've said that before.Pretty set of girls, and interesting uniforms, but I'm not sure they really fit either setting the parents are from, but I guess they could. Interesting that they seem to be benders of all 4 tribes, I know Korra was an Avatar, but I thought Avatar's only had children of their own birth tribe and the tribe of their spouse. Even if Wilbur was a bender in this world, that would mean at least 2 of the tribes would be impossible. Of course, if 2 or more of them were adopted, that might make sense. Anyway, I'm rambling again, that's obviously a question for the creators, and not for you. Great picture by the way.
That makes sense then that Wilbur is a fire bender then. If that's the case, either the other 2 are adopted, or the creator is just disregarding the rules, not that there is really a problem with that.