What is the ruling on a brother receiving haram money (bribes) that comes to him from employees without his solicitation, so that he may send it to someone who will dispose of it? And is this money permissible for those to whom it is sent, including the sister?

Accepting a bribe is forbidden due to the general evidence prohibiting it, and because it entails silence regarding and affirmation of evil. It is obligatory to refuse a bribe and return it to its giver. Giving a bribe to the poor does not make it permissible to take it, for a person is not allowed to deal in the forbidden in order to give charity. If the recipient of the bribe repents and disposes of the illicit money by giving it to the poor and needy, then there is no blame upon them for taking it, and it is lawful for them.