visa for wife on open work permit

Hello every one

i am a student of MBA and i wish to bring my wife to canada so i am applying for the "open work permit" for her. all the documents are ready . the problem is that we have nikah nama in English. so is it necessary to get the nikah nama registered and obtain marriage registration certificate from the SDM office in delhi or can the nikah nama attested by the ministry of external affairs will hold the same value. the consultant insist on getting the registry certificate so that we dont miss any chance. the problem with the nikah nama registration is that we get a 30 days notice period and both husband and wife has to be present at the appearance and the registration time. its very much impossible for me to stay for so long as i will have to miss my semester. please advice what to do .i would really appreciate ur genuine advice thank you all