What are my options with regards to how my grandfathers will has been carried out?

My grandfather passed away in 2011. In his will he left 1/3 of his house to be split between my 2 brothers and myself. My aunt (who received 1/3 of the house as well) right away moved her daughter into the house. We have not been paid anything and to my knowledge no rent is being paid. My aunt intends to buy the house, in 2013 they sent me legal papers with a purchase price of 225,000 which is below the market value. At the time I signed the papers agreeing to that sale price and assumed I would receive my cut. One of my brothers also signed agreeing, and my 3rd brother did not sign it. To this date I have not been paid, the sale hasn't been completed, and my cousin is living rent free in this house. What are my options to either get my cut, or can I force that rent be paid until things are settled? Is there a statute of limitations when it comes to these matters? I'm getting frustrated with the situation.