How can reconciliation be achieved between the condition of justice among wives for the permissibility of polygyny, and the validity of a second marriage without the knowledge of the first wife, along with the question of the extent of injustice in not informing her compared to informing the second wife of the first one's existence, and is it assumed that the marriage is void if the condition of justice mentioned in the verse: "But if you fear that you will not be just, then [marry only] one" is not met?

It is permissible for a man to combine four wives, provided he is able to support them and be just among them in lodging, and in whatever expenses and gifts are possible. He is not obligated to inform his first wife of his new marriage, but it is recommended to do so to appease her and consider her feelings. If he does not inform her, he must be just between the two wives. This is possible for some people depending on the nature of their work or travels. Otherwise, he is not permitted to practice polygyny if he cannot be just, because injustice will be darkness on the Day of Resurrection.