Is it permissible for a father to register a plot of land he owns to his male children only, while there are daughters and another wife, and everyone agrees to it, knowing that a large part of the land was built upon with houses from the male children's money?

If a father singles out some of his children for certain properties as a gift, this is forbidden by Islamic law and is considered an act of injustice and oppression, based on the Prophet's (peace be upon him) saying: "Fear Allah and be just between your children." This is also because injustice should not be witnessed. Preferential treatment is prohibited even if those deprived agree. However, preferential treatment is permissible if the father knows the deprived child's consent and fears disobedience from others due to their weak faith or poverty.

As for dedicating something via a will, it is not valid for an heir unless the other heirs agree, based on the Prophet's (peace be upon him) saying: "Indeed, Allah has given every rightful person his right, so there is no will for an heir."

Regarding the children building houses on the land, if this was done with the father's permission during his lifetime, then the value of the land they built upon should be deducted from their share of the inheritance. However, if the construction was after the father's death and without the consent of the heirs, then they are transgressors. In case of dispute, it is advisable to refer the matter to the Sharia (definition) court.