Is Zakat obligatory upon a sick woman whose father does not provide for her, and her siblings are responsible for her and her mother's expenses, and she possesses a sum of money?

"Whoever possesses the minimum taxable amount (nisab) of wealth (85 grams of gold or 595 grams of silver) and a full lunar year (hawl) passes on it, zakat becomes obligatory, even if the money is designated for marriage or medical treatment. Zakat does not diminish wealth; rather, it increases it, as Allah Almighty says: (خُذْ مِنْ أَمْوَالِهِمْ صَدَقَةً تُطَهِّرُهُمْ وَتُزَكِّيهِمْ بِهَا) 'Take, [O Muhammad], from their wealth a charity by which you purify them and cause them increase' (Quran 9:103). And as the Prophet, peace and blessings be upon him, said: 'Charity does not decrease wealth.' It is also a cause for healing from illnesses."