* I haven't disclosed about my 1st marriage to my wife and don't intend to do so as she comes from a orthodox family and it might affect my relationship specially with a child now. I have a fear that if she is called for an interview there are chances of the immigration officer asking her about it. How can I avoid this question? Is it ok if I request Immigration to not discuss this with her at all?
You cannot ask immigration to not ask her about it - because then they will for sure, and they will also take it as a sign that your relationship is not genuine, and refuse the visa.
You have to tell her. 1. A previously unmarried woman in an arranged marriage with a divorced man: in India this is considered a big red flag. I have seen appeal cases where this mismatch between the spouses' marital histories was enough for the visa officer to question the motives of the applicant. The VO wonders why any family would agree to such a match - and the most likely reason is just so the applicant can go to Canada.
2. And in your case, the wife doesn't even know about the previous marriage, so that means the parties to the arranged marriage were not being completely honest with each other. In countries where arranged marriages are normal, the VOs will accept them, but they then expect the arranged marriage do be completely according to tradition.
In any marriage, if one spouse does not know about the relationship history of the other, it is considered a red flag.
3. Because of the divorce, there will almost certainly be an interview, and if there is an interview, the VO will ask your wife about your previous marriage. If she doesn't know about it, the VO will reject the PR application.