My understanding is this: Grandma Jiang's house was originally her parents'. After her parents died, she was inherited by her three sisters. This old villa has three floors, one for each of the three sisters, and the second floor in the middle for Grandma Jiang. After the two sisters died, the part belonging to the elder sister was inherited by the two nephews respectively. Which part of the house belongs to the two nephews and which part belongs to Grandma Jiang? It should be notarized when the two sisters died, otherwise it will not be inherited. Although the property right belongs to three people, it needs the consent of three people at the same time, but it doesn't have to be donated, because grandma Jiang donated her own part of the property right, which has nothing to do with the two nephews and doesn't need their consent.
Because the sale requires the consent of three property owners, and one of them is the state, it is almost certain that the house will not be sold, which is really gratifying.