Property Dispute

Hi I just need suggestion on my family property dispute. My family has 2 brother and 1 sister my grand father died in 2014 before his death he made his will for his 30 year old property ie 2157 Sq feet (haryana), he distributed his house in two parts 1078 sq feet equally and mentioned in the will right side for his one son and left for his other son and clearly mentioned which part is for younger son and which one is for elder and he helped his daughter in making his own house after her marriage that's why he didn't mentioned any thing in the will about his daughter and planned to give cash. Grand parents stayed with his younger son in their entire life earlier in own property (haryana) and when younger son is posted in Delhi(rented house) grand parents even then stayed with him and elder son stayed in other city and never took care of their parents in his life after posting of younger son and grand father death elder son came and started staying in own portion of his property and now younger son want to sale out that half own portion and elder son is not letting him with different excuses that in his part of property they don't have washroom and asking younger son to construct washroom for him, now my grand mother is looking for legal advice and looking at the crisis thinking of selling the whole property and distribute equal amount but elder son is still not agree with this and not even ready to leave the house for selling. Please suggest