Co wives'

In islam

If the woman agrees to a co wife ion a joint decision, then its halal...however, if the first wife disagrees to a co wife, then its in-permissible......unless agreements' and or arrangements are met.

The agreements are for the first wife to make...and the agreement has to be clear and with clarity of certified knowledge of the deen, if an agreement was made, when knowledge was lacking, in relation to other matters' regarding health beauty and maintenance, then this is thereafter invalid, as the lack of knowledge would have been insufficient to make such arrangements'...without furthering consent...I think you get the picture....

And that an illegal sexual conduction, is still an illegal sexual conduction, when fully adhering and in full awareness of deen and matters', however, if there was ignorance from before hand, without a hidden agenda then the principle of deen changes again.