grandchild
child's child. Avoid using with "relative" (P1038): add item for child instead and list there (both with "child" (P40))
grandson
male grandchild. Avoid using with "relative" (P1038): create the missing generation instead
granddaughter
female grandchild. Avoid using with "relative" (P1038): add item for child instead and list there (both with "child" (P40))