So after much advice both here and from my twinny group, here's the gastronomic update:
Z ate both her breakfast and dinner today. For breakfast we had bananas and apples with a tiny bit of oatmeal mixed in to make it a little thicker. For dinner it was squash and avocado mixed with 1/4c of oatmeal made with formula, but it was pretty lumpy.
So perhaps it's just that she wanted something with a little bulk to it and I've been making everything super smooth.
Also, just in case you cared, they both had gigantic poops today. Poops that could have been made by a much larger child. I'm not sure where all the poop came from. I was a little scared.
I made a batch of bananas and carrots today to feed them for the next week or so. C loves the hand blender so I usually let her chill in the kitchen in a seat while I do it. She's a wierdo