Property Related Frauds : How To Get Saved

My mother, her 3 sisters and two brothers have their names in the Property document (7/12). This property was passed from their father/mother to them. 1. Does all co-owners have equal rights in property. Including Women’s. 2. My elder Mama (elder brother of my mother) expired two years back and his name is replaced by his sons, daughter and wife. They sometimes try to sell the property, they take the token amount from the buyer but nobody other than elder Mama's family come to know about it. Even though the property is not sold they try to do it by taking a token amount. Is there a way to know about these deals so that other co-owners be aware of each deal that was happened or going to happen? 3. Is there any chance that without consent/sign of other co-owners, they can sell land. by fake signs or such malpractices. How to avoid these before happening such an incident.