Promotion from backdate

Well I work I in Central Railway and is governed by the Railway service and conduct rules 1966. Recently I have been promoted to grade pay 4600. During the 6th pay commission two posts have been merged. He posts are CMA-1 (5500-175-9000) and CMA-2 (5000-150-8000). Now the process of promotion started from 2011 when CR of all of us was asked for in headquarters only those of CMA-1 was called in headquarters. At this some CMA-2 raised objections as to some of them claimed that since the posts have been merged so they are seniors so not to promote anybody until seniority is decided. The matter of seniority was decided after two years and Railway board decided that CMA-1 is senior. Accordingly we were promoted during 2013 April. Our promotion date was fixed as 1 April 2013. Now my questions are:- 1. Can we claim before the Railway that we have to be promoted from an backdate as the process of initiating promotion was started from an earlier date ? 2. Is there any relevant judgement in CAT, High court or Supreme Court in this matter ? 3. What is the procedure for filing this case in CAT ? Kindly answer the questions serially ?