Gift of undivided shares of property

Sir my father expired. my father got property in three ways. 1. property by the partition between his father and brother. 2. Gift property from his father and he had the possesion right. 3. property through the unregistered will from his father. As per the unregistered will, that property belongs to my father and his brother. After the death of my father, based on this unregistered will, me, my mother, my grandmother (we three are the legal hier of my father) and father's brother jointly sold some property and some of the properties are remain unsold and they are undivided between all of us. Note: 1. still all the above properties are undivided. and they are under my possession right. Based on the aforesaid property i have some doubts. 1. whether my grandmother can give her undiveded share to his younger son or not for all the aforementioned types of properties. If such a gift of undivided share is not valid, please guide me in the same. (Note: 1. My grandmother had ancestral property and the same has been gifted to his younger son's son 2. My grand mother crossed 85 years).