This thread is still going, with the OP's sister cast as a sullen greedy materialistic tat-lover who has sulked for five weeks because OP refused to give her three tiny token presents to rest victoriously upon her grasping entitled children's "they have everything" already massive pile of useless mountains of throw away gifts.
I don't believe this is about presents at all. In reading the many posts of the OP, I don't get any sense of loving fondness on OP's part toward her nephews, whom are still pretty young children. There is a sense instead of resentment and contempt from the OP toward her sister and her sister's children. OP has alluded to her sister's apparently happy home life which wants for nothing, all material needs and desires fully endowed with her children pampered and entitled little brats who don't need presents for Christmas in comparison to her own 15 year old ds who is mature, nonmaterialistic (but still worthy and deserving of materialistic presents though), and is not like those awful cousins of his, he sees the beauty of OP's generous sacrifice of nephews' gift fund to a charity. OP's struggle as a single mother is also humbly offered as a noble contrast to her sister's paved way of ease.
Envy is kind of an ugly vice so the person who envies often covers resentful jabs with a veneer of virtue. This withholding of presents, which is really not about presents but about the withholding of genuine love and regard for the sister and her children, is OP's way of taking a little jab at her sister and looking noble while she's doing it.
If, as OP suggests, her sister could easily buy whatever she wanted for her children herself, then that puts the lie to the accusation that the sister is greedy for "more" presents. In truth, I would bet the sister wants the sentiment, not the gift. She wants to know that OP has a sincere regard for her children. That missing regard, replaced with OP's cold logic that OP's nephews need absolutely nothing from their aunt at Christmas, not even a homely bag of homemade cookies, not even an experience of some kind that doesn't cost money that the aunt could share with her nephews with love, no, the OP refuses to "give" anything at all, under the guise of a noble charity announcement, with OP pretending to not understand why her sister was upset, is what has escalated this to the sister not even willing to speak to OP, what good would it do? OP is noble, sister is materialistic twat lover, and that is that, according to OP. Sister has no choice but to leave OP to the warmth and heat of her noble gesture. Out of all the myriad ways OP could have budgeted this donation, which is a very worthy donation and no one disputes that, she chose to budget it from her nephews' present money, to make a statement, to take a little jab at her sister, accusing her sister that she only wants presents because she is materialistic and grabby, while OP is giving from her small income to help people in true need; that cold, calculated "noble" gesture with the underlying dismissiveness toward her young children who "need nothing" whatsoever according to their aunt, is what the sister is upset about. The sister senses the OP's resentment toward her children, you can take that to the bank.