While going through quarantine/introductions, I had one cage (the cage the girls live in now) which was significantly bigger than the other. Once quarantine was up, and I was introducing them to each other's smells, I started swapping cages. It made me not feel so bad that someone was cooped up in a smaller cage all the time.
Also, welcome! Glad to see you've got two gliders, got them on a good diet, have gotten them checked out by a vet, and know about quarantine/introductions. :]