What is the ruling on the action of my grandfather, who designated plots of land for his male children to the exclusion of his female children, and does sin fall upon me, or upon my father, or upon my grandfather, and what is the solution to get out of this predicament?

The gift (hiba) that took place during the grandfather's lifetime and was acquired by the male children is valid. Designating males for the gift to the exclusion of females is disliked (makruh) by the majority of jurists and forbidden (haram) by the Hanbalis, but the gift remains valid and enforceable. If the giver dies before reclaiming the gift, it becomes established for the donee and binding, and the remaining heirs have no right to revoke it. This is the relied-upon opinion among the four Madhhabs. Shaykh al-Islam Ibn Taymiyyah, however, holds that it is not permissible for the child to take the surplus and he must return it.