Flightless Or 'runner' Budgie Laying Eggs

Hello All

I'm new to this forum and I'm after some advice.  I have 8 budgies (3 females and 5 males) in an outdoor aviary.  I have been given some of the birds, one of which is a flightless or 'runner' budgie - I think because of a slight wing malformation.  She's called 'Buzz' and she manages to potter around quite happily.

Recently, because one of my hens is very broody, I've put in some nesting boxes (the 3rd female is quite old but will push the broody female out of her box if she hasn't got one of her own ) I thought Buzz might just hang out in hers, but she has been spending quite a bit of time in it - and now has 2 eggs which she appears to be incubating.  Has anyone got any experience of this?

Thanks