Is it permissible to take from the husband's money without his knowledge to give to a needy sister, knowing that the husband is charitable, financially well-off, and has designated a bank account for his wife to take from as she wishes?

A wife is entrusted with her husband’s money and is responsible for it. It is not permissible for her to take from his money without his permission to give to her sister. However, if the husband gives her money as a gift or as her obligatory maintenance, she may dispose of it without his knowledge. But if he gives her money for household expenses, she is not allowed to give charity from it except with his permission. She can inform her husband that she knows people who are in need of charity without directly mentioning her sister.