Isn't the surviving Cockatiel mentioned the conscious holder of Christina's mum - also called Christina? The bird knew the phrase: 'Christina lives' unlike the others so that must mean the mother was the cockatiel trying communicate that she survived - just not as a human. Her concious was lost from her body but entered the animal. Who knows.
Overall, seriously gripping game plot. Bravo!
I don't think I will ever find out the reason characters in upgrade games like this earn money by covering distance. I'd be a millionaire right now if the same logic applied..