Expert suggestion needed for noc

Dear all, I am in big trouble and I don't know how to move further. ...currently I am working in military engineering services on civilian Jen post (4200 grade pay) since feb2015, I am in probation period (tempory right now)....earlier in 2014 I had given railway exam of senior section post (4600 grade pay) now the result published and I got selected. ..my problem is my parent department (military engineering services ) not issuing the noc for railways and if I disclosed in railways that I am currently working than they will definitely ask for noc....if I hide it than it may create problems in future if disclosed. ....I requested u all to plz guide me what are the options available and which is the best among them...