I changed the lining to white craft paper, A3 so it only takes 2 sheets and they fit smug in the bottom. Unfortunately my cage doesn't have a floor grid, my old cage has but it's too small to use in the big cage, I've been looking into getting or making one for a while but I can't find one that fits or the right materials.
I'll try and get a paper shredding toy to place further up the cage.
Their appearing much healthier. Their poop is a colour and consistency I'm much happier with, and I've been giving them fresh veg daily.
They are going through a molt but I'm doing what I can to help them through it. I've noticed that some of Yurio's new wing feathers are a dirty white instead of the bright yellow they were before so I'm going to look further into that.