What are the limits of the legal responsibility of a brother towards his orphaned sister whose affairs he manages? And is he obligated to check on her daily, or is visiting her two days a week sufficient?

If the father dies, the guardianship transfers to the brother, but there are details and differences between guardianship over wealth and guardianship over the person.

As for taking care of the sister’s affairs (sponsorship), jurists have differed on its extent:

Malikis and Hanbalis: The brother’s right of sponsorship over his sister continues. Abu Hanifa and Shafi'i: It ceases upon the sister reaching puberty. Hanafis: A girl is not allowed to live alone if there is fear for her safety. Ibn Abidin believes it is necessary for her to be taken in by her relatives who are capable of protecting her due to the corruption of people.

Conclusion: A sister has a right of sponsorship over her brother, which includes attending to her affairs, offering advice and guidance. He must observe her, ensure her well-being, provide for her sustenance and clothing, and he is not allowed to sever ties with her. It is permissible to leave her alone if she is secure and in a safe place; otherwise, it is not.

Financial Guardianship: It ends when the sister reaches puberty, and she has the right to dispose of her own wealth.

Guardianship over Marriage: The brother has guardianship over his sister's marriage.

Maintaining Kinship Ties: Kinship ties between them must be maintained according to custom.

Advice: Do not deal with your brother based on a policy of rights, but rather with connection, benevolence, gentleness, and showing him gratitude.