Ohhh, so sorry about Maui passing! She was gorgeous! That picture looks as if somebody colored her like that on purpose!
I would not worry too much about Irwin's weight, John. I once took in a lovebird which had been starved (his mate had also died from it] and he was always way too skinny for the rest of his life. Starvation does something to their internal organs and even when you feed them regularly, they never quite 'come back'... (he had also been left with a serious neurological problem from it]. Give him millet instead of sunflowers - and white bread - and wheat grass (grow it yourself in a little tray in his cage, if you can].