Thanks, CountessKate, for helping me understand Maria Theresa. I truly have quite a hard time understanding her psyche. Her contradictions simply astonish me, that's why I have hard time just "swallowing" what many authors state about her, i.e. idealising her. I think what she lacked was also self-reflection. If her children were so ungrateful and rebelled in different ways, she never appeared to realise her role in such. I understand that she was monarch and used to being blindly obeyed but she did have some analysis done with her spiritual adviser, Taroucca. It's a pity she didn't seem to continue with it... it seems that she only did because she wanted to analyse why the Frederick the Great got Silesia, after all. I think what Isabella of Parma said, that MT lacked trust in herself (in modern parlance self-esteem) and she transferred such to her children, is true.
Even with Franz Stephan, she played "tricks" on her mind, perhaps to make herself feel better because she didn't treat him very nicely. After his death, she claimed that all her actions were centered around him but going into an alliance (which FS abhorred) with France permanently put a stop to any remaining hopes FS had in recovering Lorraine. And that was just one example. Another instance is that she called her cousin Maria Antonia of Bavaria (Electress of Saxony) earlier as her "dear cousin and friend" during the Seven Years War while much later on, to rally Marie Antoinette to Bavarian cause of Austria, she called the Electress an "intriguer". Let's not go into her declarations of spying (to her son Archduke Ferdinand) as not good: that people, even servants, have the right to privacy but she engaged on it for years. And if she didn't like to hear gossip (i.e. bad things) about other people, why was she so ready to believe all the stories coming to Vienna about her children abroad?
I find MT and Marie Antoinette's correspondence to be sad, laced with professions of love but both sides playing a game with each other. So I have never been convinced that Marie Antoinette did right in "charming" her mother in letters. I don't think Maria Amalia was always right in disobeying her mother on certain matters but, at very least, she was honest (see reply to her mother's 23 rules of conduct). In that respect, I agree -- I can see that their relationship was the healthiest in terms of honesty. Both sides eventually knew their limits as far as the other was concerned: MT could never dictate to her as long as Ferdinand of Parma shielded Maria Amalia, and Maria Amalia not given permission to visit Vienna (and according to what I have recently read, didn't receive that many presents as some of her other siblings from their mother). I read that MT destroyed majority of her children's letters but kept many by Marie Antoinette and Joseph II. I have to say, Maria Anna seemed to love her mother - she didn't feel loved by her but Maria Anna wanted it nevertheless. I have not read anything about Maria Elisabeth wanting her mother's love after she got disfigured by smallpox.
I have to say though that I've read many accounts stating that MT had a terrible temper even as a young lady (newly married to FS) so it was there all along, old age and her ill health simply aggravated it.