How can one deal with an unmarried sister who instigates problems and blames her father for her not being married, thereby making life hell?

It is recommended to supplicate frequently and persistently to Allah Almighty, while taking the means and conditions for the supplication to be answered. It is reprehensible for a father to place obstacles in the way of his daughters' marriage, as this may lead to spinsterhood. If the father has caused the delay in marriage without a legitimate excuse, he has done wrong, but it is not permissible to reciprocate by harming him, for disobedience to parents is among the gravest of sins. During tribulation, one should be patient and not discontent. The elder sister is advised to fear Allah and to be gentle in her dealings, and the questioner is advised to occupy herself with remembrance of Allah (dhikr), seeking forgiveness (istighfar), and reading beneficial books such as "Don't Be Sad." It is permissible for a woman, according to Islamic law, to seek out potential spouses or to offer herself in marriage to whomever she desires to marry.