Can a property be sold without the owner knowing of it

Hi sir, we are 4 brothers & 1 sister, my grand father has one son ( my father) and 2 daughters (married 40 years back). my father age is 75 years still alive. we have agri land from my grand father which is his own property, and one commercial shop & house of my father, he purchased 20 years back from joint family income. 1).can we 4 brothers partition agri land legally without my father permission.2). can i get share on houses legally since he purchased from agri income. 3). can my father is legally eligible to get share on my grand father property. pls clarify sir ASAP and let me know if any questions.