My sister is a teenager and behaves with indifference

My sister is a girl of sixteen years old. We lost our mother when she was five and she was very attached to her. My father married another woman and she now lives with my sister in the same house, but for some time I have noticed that my sister behaves strangely in a way that goes against our morals and traditions at home. She once asked to speak to her friend's brother while she was talking to her, and I thought she was joking with me, so I took the phone from her and indeed heard his voice speaking. She also went out with another man she knows in his car to give her a lift home, and when we reproached and scolded her she told us he had not done anything to her. We fear she will go astray and she rebels against our guidance. My father is also not sparing in giving her money. Please help me.

The reply
Dear sister,
Many of us are not skilled in the art of dealing with adolescents, particularly girls, for this critical stage of life is a crossroads in forming a girl's character. This stage is usually accompanied by a pursuit of freedom from the restrictions of others, by rebelling against them and disobeying them, and by intense emotions. This does not mean leaving her as she is and letting the consequences of her behaviour decide; rather she needs her family to understand her, to listen to her and to urge her towards what is right and wrong. It is not enough for the father to be a means of spending money without follow-up and flexible supervision. What the girl lacks and suffers from is emotional and psychological deprivation, which has made her behaviour turn out in an undesirable way. It is essential to meet her psychological needs such as love and security, to increase her self-confidence, to strengthen her religious sense, for the father to set aside more time that brings him close to her, and for her stepmother to be trained in establishing a relationship of friendship between them.