Dear sir as my friend was married and then he married an other girl and did not tell to his wife and parents unfortunately his second wife is sister of his first wife now he is confuse can he keep both wives or will have to divorce one of them if he has to divorce one of them then he should give to his first wife or second, please reply of this question

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

The jurists stated that whoever marries two sisters at the same time by two separate contracts (and one preceded the other in time), then the marriage contract with the second wife becomes invalid whereas the marriage contract with the first wife is valid. Their evidence is that combining two sisters in marriage at the same time took place by marrying the second wife [so it is her marriage contract that becomes void].

Therefore, that man must separate from the second wife, because it is not permissible for him to combine two sisters in marriage at the same time because this is forbidden as clarified in Fatwa 86633. However, he is not obliged to divorce his first wife.

If we presume that he had children from the second wife, then they should be traced back to him as he married her while believing that there are no legal impediments to her marriage.

Finally, it should be noted that if a husband wants to marry a second wife, he is not obliged to inform his first wife or his family about it. However, he should authenticate the marriage as a way of preserving the rights of the wife and children if any.