Is it permissible to visit an endowed land that has been seized, sold, and built upon, knowing that not visiting may lead to a severance of kinship ties?

If your husband's brother bought an endowed land without a legitimate right, he has committed a grave sin by usurpation, for the Prophet, peace and blessings be upon him, said: "Whoever usurps a handspan of land unjustly, Allah will encircle his neck with it from seven earths on the Day of Resurrection." You must advise him of the necessity to repent and return the land to those responsible for endowments. It is not permissible for you to visit him on this land or benefit from its facilities, as this entails acknowledging a wrongdoing and aiding in sin. If scholars agree on the impermissibility of praying on usurped land, then how about benefiting from it? Your not visiting him on that land will deter him, and if a rift occurs, its sin lies with the one who insists on disobedience. Kinship ties can be maintained through other means.