clarification related to division of ancestral property

We have a property which is on a lease. The property was initially owned by my great-grandfather and then he had written in the property document that the property belongs to his elder son i.e Mr A and he should give a portion of the property to other two brothers Mr B & Mr C. Now all the three grandfathers MR A, B, C are expired. The property through internal understanding is divided equally among all the three brothers. The property is occupied by all the members who have stake claim to the property. Please advise how do we proceed to add our name to the property. Mr A had 2 son and 1 daughter 1 son is dead 1 son is alive Mr I is alive daughter is alive and has given POA that she has no claim in the property, Mr B had 5 sons & 2 daughters. 4 Sons and 2 daughters have given up their claim and now Mr K son of Mr B will stake claim to the property . MR C has two son and 1 daughter again 1 son and 1 daughter have given up their claim and now only Mr M son of Mr C