What should I do regarding my parents' lack of attention to my siblings' upbringing, and my sisters wearing immodest clothes in a society that harasses girls? And should I impose modest dress upon them, or is it sufficient to advise and remind them, and how many times should the reminder be given?

The sisters' going out adorned in front of non-mahram men and their wearing short clothes is forbidden and brings down Allah's wrath. The guardian must oblige the woman to wear the hijab and prevent her from displaying her adornments. The parents' responsibility towards their daughters is immense. The questioner should inform his parents of their responsibility before Allah and advise his sisters, reminding them of the hijab and modesty, and warning them against displaying their adornments. If he can discipline them and prevent them from going out in such a state without causing greater harm, then he should do so. It is permissible to boycott them for disciplinary purposes if he believes it will be effective; otherwise, not. If the parents do not allow him to take charge, then advising and reminding them is sufficient for him. He should not abandon his studies or work because of this; rather, he should continue them while offering advice. He must pray for their guidance. There is no sin upon the questioner as long as he has fulfilled his duty of enjoining good and forbidding evil within the শরঈ (Sharia-compliant) limits.