Is it permissible for the questioner's wife to buy wedding provisions for her sister from money of usurious origin that the questioner owns and wishes to dispose of?

Unlawful money must be disposed of by giving it as charity to the poor, or by spending it on the welfare of Muslims. It is permissible to give some of this money to the wife's sister if she is poor and in need. However, if she is wealthy, it is not permissible.