Over the last couple of months, it's become clear to us that she has learned to manipulate us with screeching, flailing, and generally complaining and being obnoxious.
That's GREAT. She's figured out that she can interact with her environment and that she can make things happen. Believe it or not, that is a wonderful thing.
I wouldn't look at responding to her needs and desires as teaching her that tantrums are a good way to get what she wants. I'd look at responding to her needs as teaching her that she can and should communicate with her parents, who will be responsive and helpful if they can be. Right now, tantrums are how she communicates her strongest desires. No, they're not the most pleasant. But they're all she's got.
Babies can have strong feelings without any control over them. It's not fair for you to expect her to learn to express herself in other ways right now. I would not attempt that at this point. Babies don't need discipline. They need loving and responsive parents.
