What is the ruling on the wife's family deceiving and concealing from the husband a serious illness their daughter has that prevents marriage, and what should the husband do if he discovers this after marriage? Also, are the wife's family entitled to demand all of her rights in the event of divorce if marital life becomes impossible due to this illness?

It is forbidden for the wife's family to conceal a defect from the husband that would invalidate the marriage. If the husband discovers the defect after consummation, he has the right to annul the marriage, and he must pay her full mahr (dowry), which he can then claim back from the wife's family. In the case of annulment, the wife is not entitled to maintenance. If the husband does not annul the marriage and divorces his wife without stipulating the forfeiture of her rights, she is entitled to all the rights of a divorced woman. However, if he divorces her and stipulates the forfeiture of some of her rights, only what she has forfeited will be waived, and she will retain all other rights.