What is the ruling of the Sharia on the claim of a daughter's children for a right of their mother in their grandfather's inheritance, while they know that their mother had taken her full right during the lifetime of the inheritor?

If the adult, sane, and mature mother willingly and contentedly relinquishes her share of the inheritance, her children have no right to claim it, because what is forfeited does not return. However, if her relinquishment of a share less than her rightful legal share was due to shyness, fear of estrangement, or coercion, then her brother must give her her full right, based on the Prophet, peace and blessings be upon him, saying: "The property of a Muslim is not lawful except with his willing consent." It is not permissible to pressure daughters to leave their inheritance for their brothers.