What is the ruling of Islamic law on retracting an agreement to divide land after the father's death, and requesting a new solution after securing ownership of the lands?

If the father gifted the land to his children during his lifetime and in sound mind, and they took possession of it and agreed upon its division, then this division is irrevocable and is called a "division by mutual consent" (qismat al-taradi). However, if the father did not gift the land and asked them to agree on its division after his death, then it is considered an inheritance (tarikah). What was agreed upon before his death is merely a promise, which is recommended to be fulfilled. Nevertheless, any heir has the right to claim their lawful share if they are not satisfied with the promised division.