Hello.
I haven't heard of anyone else on the forum with a situation like you are describing.
You say that you changed your son's and daughter's names, and dates of birth. This is most unusual. I think it's very normal in those circumstances that INZ need to know just why you did this, and how you got the new documentation. Part of the 'character' requirement for any NZ visa is to be completely truthful with INZ, and any time they realize an applicant has avoided telling them everything, it's likely to be considered fraud. So you will have to reply in a completely open and honest way, and give them all the help that you can.