Does working as a secretary for a company that sells prohibited goods, such as alcohol and cigarettes, make the salary unlawful, especially given that I have an infant daughter and no other provider? And what should I do regarding this job?

If secretarial work does not involve assisting in the sale of prohibited items, then it is permissible, and the salary is lawful. However, if it involves cooperation in the sale of prohibited items, then it is not permissible, and a portion of the salary equal to the extent of assistance in selling the prohibited items is unlawful. As for the mixed wealth of a father who worked in selling prohibited items, it is permissible to benefit from it.