Property matter

my father have three son.Father have purchased the agricultural land on his name from his own income & also on my mother name. In 2000,My father and his third son has given money to second son to purchase land in town on promises to give    few portion of  land to third son.  now second son has refused to give the land of town area  nor returning money to father or taken from third son. Now father & mother  has decided  to give the agricultural  land to third son from the share of second son also few agricultural  land to first son. now what to do once  first & third son have no money to take the agricultural land as gift or to purchase from father.

Nawal