Revert back in job

Hi, i am here for you valuable opinion for case of my father , he is govt servent in uttarakhand. Actualy today he got letter from authority regarding revert back his post to lower post in the matter of that at the time of joing his service he hided some fact about his service to get unapproprite benifit. Actual my father joine an organisation in 1984 on a post on daily wages & in 1986 he promoted in higher cadre on daily wages employee. In march 1991 my father was regulalized on post on which he was working that time means as on march 1991 on basis of current designation according to master list prepared by organisation in 1986. Means my father was working on same cadre since 1986 to till regularization i.e march 1991. but the affidavit that was provided to fill wad in september 1991 to my father and in that affidavit there were no format of column to disclose ur working information work desigbation with duration on diffrernr different time and by the time my father had no written information about his earlier service designation on daily wages so my father mentioned since 1984 till now( at the time regulation ) he is working on the post that was given to him in 1986. In the mean time on G.O was came in i.e 31 may 1991 According to that G.O at the time regularization the designation of your first day of service whould be considered. On the basis of that G.O now in 2016 they passed the judgment of revertback of service of my father regularization on lower post w.e.f march 1991 with allegation of hiding fact to get missapropriate benifit even criteria of regularization of my father service was current cadre/post at the time of master list preperedby organisation in 1986. So my question is that is it right decision taken by administration of organisation & I also want to know that affidavit filling date can be bade to justified that that G.O i.e may 31 1991 whould be applicable to decide the cadre/ post which was given in march 1991. One thing seems clear here that allegation of hiding fact is not applicable as regularization date is march 1991 and affidavit date is september 1991 . He got regular in march much before filling an affidavit so how he could get benifit of hidding fact. I also want know that is adminstration is not answerable of delaying or providing affidavit for filling so late about six month. Can we challenge this decision in court and get stay order on this decision. Also tell me that my overlook on the issue is how much right.