[becca623]

I have a relative like that. She refuses to bathe her bird, his water is always dirty and the bowl is too small for him to use for bathing, feeds him only sunflower seeds and millets, and won't give him toys because her last one didn't like toys. (eye roll) Anyway, I gave her pellets, cooked mash, birdie bread, bought a book about tiels for her, and washed the dust off his mirror (which she then complained made him too noisy). I give him fresh water whenever I visit. It doesn't do any good because she has had birds her entire life so she knows what's best. Plus, "he's spoiled". (She's in her 70s) Then she complains that they don't live long enough.
I say offering some good foods to them and speaking directly to the child about the importance of proper diet and care are a good start. Maybe you can convince the child to take up the better diet cause. Like one of the previous posters said the parents are more likely to listen to a nagging child than a kind hearted neighbor. If they still won't take better care of the bird maybe they'll "unload" it on to you. I know a man who got one of his green cheeks that way. Anyway, just know that you are doing your best. It's all you can do.
Good luck, Rebecca