So I have a surprising update. Logic and reasoning did indeed work out with the AB.
In my case it was the following, I got a letter after 6-7 months stating that they need to verify my marriage certificate and birth certificate. They then asked for 355 Euros additionally for this verification... Despite my initial protest that my wife joined me ONLY after the stipulated
marriage certificate verification, so the AB MUST have a proof somewhere, the concerned authority told me that either i ask the consulate which did the verification to contact the Einbürgerungstelle
directly and send them a copy of the verification or pay for the whole thing again... He told me that yes i know it can be painful because we germans are tooo genau...
So i decided enough is enough and went directly to the person who was responsible for issuing my wifes visa. I could not get in touch with her at first directly, but had to go to the room number which had come up at the display. There i explained to the person the entire situation and said firstly, My wife came to germany for which the minimum requirement was verification of marriage certificate. Then why must it be verified again? He was a nice person and he directly contacted the Einbürgerungstelle (which is only one floor above) and informed him about that and said incase you need proof of marriage, please check the file with my wifes details... I was told that i would hear from them the next day itself and i waited. This wait lasted two weeks and i went again today to the visa stelle and told them the same thing again. This time the sachbearbeiter was a different person and she again contacted the Einbürgerungsstelle. Finally, the person who handles my Einbürgerung asked the lady to send me directly to him.
When i went there, to my surprise, he said well see you pointed out that your wife came by nachzug and we do indeed have a proof of your marriage so it need not be done again.
But now my birth certificate may indeed need verification which he says will inquire again and will let me know how much i need to pay for that. I am only happy that hte first thing worked out and logic did indeed win. Faith is restored...