Who Will Get My Grandmother's Property

My grandfather has 2 daughters and 1 son, he wrote in his will that his land should go to his wife, his some other land should go to his son after his death. After his death in 2003 all happened according to the will. Now my grandmother is willing to transfer the land on her name to her 2 daughters, can my grandfather's son or my grandfather's son's son stop this transfer of ancestral property or they don't have rights. My grandfather's son's son was not born during 2003 transfer.