Thanks for the prompt reply, Esso's mommy. My birds are on an 80/20 diet of seeds/veggies, respectively. The young bird looks fat because she loves to eat and does not like to fly as much even though she wants to be out of the cage, particularly when she sees her friend is outside flying happily.
Funny thing is that the young bird always want to sample both seed dishes and picks out the choicest seeds. So, the old bird usually ends up being chased away, but she seems to do this "voluntarily". I say that facetiously because it is like second nature to her now ... when the young bird is only half way near her, she hops off the dish and starts heading for the other dish. Honestly, I believe she is afraid of getting pecked.
One time, when she was eating, but the young bird was locked outside the cage but looking in, she just kept eating with a smirk on her face.
LOL!!