Can a woman place this condition at nikah, that she will take full custody of the children in case of divorce and allow their father to visit them only after her permission, and in return she exempts him from bearing their expenses in any way?
This can not be set before the marriage takes place. This can be said once the divorce takes place and the children are already there. She can exempt the husband from the children’s expenses providing that she may keep the children. She can’t prevent the father from seeing his children unless she approves it. This is not permissible.