About Land Dispute

We, 4 people, made an agreement to another party to sell a plot of land which was not in our possession at the time of the agreement. And the second party was unaware of it. After the agreement, the second party tried to construct a boundary wall which was opposed by the possessioner of the land. And the second party lodged a case against us and the court directed us ie. (Four people in the first party) to pay the amount that was taken at the time of the agreement. But one of us hired another lawyer and filed a petition in court and made only three of us liable to pay the whole amount, how this is possible as he was one of the first party in that agreement.