Is it permissible to make a will in favor of a grandson whose father has died, despite the objection of some heirs to that, and is there a concept of preemption (shufa'a) in Islam, such that the close relative has a prior right to purchase?

The estate of the deceased is distributed among his children by way of ta’sib (agnatic inheritance), with the male receiving the share of two females. It is divided into seven shares: two shares for the son, and one share for each daughter. The will made for the grandson is valid and enforceable within the limits of one-third of the estate, and the heirs do not have the right to object to it, because the grandson was not an heir to the testator at the time of his death. The death of the grandson’s father after the testator (grandfather) is not considered a reason to make him an heir. The son who died before the grandfather is deprived of inheritance, as are his two daughters, due to their being excluded by the direct son. Pre-emption (shuf’ah) is a right for a co-owner in a property and is unrelated to kinship. It involves taking the sold share at the same agreed-upon price.