Will question

Hi 

I've a question on WILL please clarify , my grandfather property of 18 acres land is registered as WILL by my father few years back. But now my father is planning to sale some acres due to raise in price without knowing me. Is there any possibility if I can stop the sale and how effectively I can use WILL in this case and what is the best way to completely avoid this type of sales in future and how to completely get WILL powers. 
Appreciate your response.
 

Thanks & Regards