My father made a registered will leaving all his property to my younger sister, while I, her elder sister, received nothing. We are the only two daughters in a Hindu family. Why did he do this?

Under Indian law, a testator has the right to dispose of their property as they deem fit in their will. Your father’s decision to leave his property to your younger sister is valid as long as the will was made according to legal requirements. There’s no legal obligation for him to distribute his property equally between his daughters.