What are the rights and duties incumbent upon a wife towards her husband's elderly sisters who sometimes harm and wrong her, given her desire for good treatment and avoidance of injustice?

The husband's sisters have no special rights over their brother's wife. They have general Muslim rights over her, just as she has over them. It is not permissible to abandon them for more than three days, unless abandoning them is a way to escape their harm. The wife's patience with her husband's sisters and her overlooking their slips is a righteous deed and a perfection of good companionship towards her husband.