(iii) the apportionment of the said compensation among all the persons known or believed to be interested in the land, or whom, or of whose claims, he has information, whether or not they have respectively appeared before him: [ Provided that no award shall be made by the Collector under this sub- section without the previous approval of the appropriate Government or of such officer as the appropriate Government may authorize in this behalf: Provided further that it shall be competent for the appropriate Government to direct that the Collector may make such award without such approval in such class of cases as the appropriate Government may specify in this behalf. [ (2) Notwithstanding anything contained in sub- section (1), if at any stage of the proceedings, the Collector is satisfied that all the persons interested in the land who appeared before him have agreed in writing on the matters to be included in the award of the Collector in the form prescribed by rules made by the appropriate Government, he may, without making further enquiry, make an award according to the terms of such agreement.