Is it obligatory to leave the usurped village that belonged to my grandfather, and does the sin of this usurpation fall upon the grandchildren, and what are the consequences of that?

Whoever usurps another's property is obliged to return it. If it is lost, then a similar item or its value must be returned, as the Prophet, peace and blessings be upon him, said: "The hand is responsible for what it takes until it returns it." If your ancestors usurped this land and you inherited it, then it is not permissible for you to benefit from it. It must be returned to its owner or their heirs. If they are unknown, then it must be given as charity to the poor and needy. Rights are not forfeited by prescription, and failing to dispose of this property makes you partners with the usurper in sin. The family of the girl has the right to refuse your marriage proposal due to your failure to rid yourself of unlawful gains.