Is totally depriving siblings of internet access considered injustice to them, especially given their noticeable negligence in prayer and their listening to music because of it? And would the questioner be sinful for providing them with the device despite her warnings to them and her attempts to disconnect the network during prayer times? What is the Shariah-compliant solution for dealing with this intense attachment to the internet that affects their religious commitment and prayers, knowing that she is the eldest sister and fears wronging them by preventing it?

If the siblings misuse the internet and fall into prohibited acts because of it, or neglect obligatory duties like prayer, then preventing them from it is a kindness and a necessary admonition. This is in compliance with the words of Allah Almighty: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." There is no harm for the questioner to use it if it is far from prohibitions. She can allow them to use it in her presence, while persistently offering gentle advice and good admonition so that they adhere to the limits of Sharia in dealing with the internet.