God has assigned this responsibility to the parents, not to grandparents or to anyone else.
فَٱللهُ أَوْكَلَ هٰذِهِ ٱلْمَسْؤُولِيَّةَ إِلَى ٱلْوَالِدَيْنِ ،‏ لَا إِلَى ٱلْأَجْدَادِ أَوْ أَيِّ أَحَدٍ آخَرَ .‏