I am a Muslim who is going to get married to a Hindu. Though we will be first registering our marriage under Special Marriage Act but to save my father from public disgrace we will be doing a false nikah without conversion at my parents place where muslim community will be invited.
-: "we will be first registering our marriage under special marriage act" - This will be your first marriage and valid marriage. You will be govern by the SMA.
1. Now will this false nikah affect my future married life in any way?
-: It depends upon the girl's attitude.
At the time of 'nikaha' the girl has to be converted into Islam. Do not hide this fact, to the girl before marriage. If you hide this before the girl, the marriage may suffer and attract the provisions of force and fraud under SMA, and subject to void.
Your Impression is wrong. 'nikaha' can not be done between two parties where one is hindu. Conversion is a must for such marriages. Even otherwise it will not be a valid mohamedan marriage. It is very clear before all mohamedans concerned. If she not converted it will not be a mohamedan marriage.
Change of religion by force or fraud is a punishable offence, under IPC also. I am afraid that the girl may face force and fraud at the time of 'nikaha'. A mohamedan may marry a person - who is not a worshiper of fire and idoll. Hindu is worshiper of fire and idoll both, according to mohamedan religion.
Non worshiper of fire and doll means who are jews and Christians. They may marry a mohamedan without conversion.
After special marriage act, with the full consent of girl ( means without force or fraud), you may 'nikaha' her once again. It will not be illegal.
2. If later on anyone comes to know about this false nikah ,can it be misused against my father?.If yes then can there be anything which we can do to make it more soundproof.
-: yes you are right. Problem may come from the girl and her parents, not from your relatives.
At the time of 'nikaha' the girl has to be converted into Islam. Do not hide this fact, to the girl before marriage. If you hide this before the girl, the marriage may suffer and attract the provisions of force and fraud under sma, and subject to void.
I am afraid that my answer may not happy you, still then answering to avoid future problems.