Can a grandfather sell ancestral property?

My grandfather has sold 286 dismal out of 408 of our ancestral land. He still wants of sell. Currently he just took some amount of loan from one villager on few land. While taking advice from advocates they suggested to file partition suit but my question is 1. Will I get half of whole property or of current remining property. 2. If we win the case then Again we need to pay him maintenance as he is senior citizen. What should we do that he should not sell property? Is there any agreement system is available from which we can offer him money and half of grains, but he should not sell. After that agreement he should not sell our land.