Is the first wife sinful for preventing her co-wife from visiting the husband's family in the first wife's home, fearing problems, while agreeing to the husband's family communicating with the co-wife outside the home?

The wife has a right to independent housing in which no one shares with her, and she cannot be forced to see her co-wife there. As for the co-wife's presence at the family home and her visit to her mother-in-law, the wife has no right to object to it, and she can remain in her apartment. The children getting to know their father's wife and their siblings is a good thing and a mandatory act of maintaining kinship ties, and the wife has no right to prevent them from doing so. The co-wife has the right to visit her mother-in-law, and the children have the right to maintain ties with their father's relatives. The wife's objection to that is an injustice and an aggression. The wife is advised to maintain a connection with her co-wife, or at least allow her children to maintain ties with their co-wife and siblings.