fire escapes vs sprinklers

realizing the code and frankly what they might say the code now means is changing rapidly past few years and lots of these posts are a few years old Id like to know from anyone with recent knowledge about a couple things.

First is it an either or sprinklers or fire escapes and does it matter if its 2 or 3 family conversion?

I also saw someone discussing converting a one to a two family say that if the house doesnt actually have a CofO since its pre 38 say then it might be much easier to get a two family c of o if it only says one family for tax purposes? My title co could not find a C of O but its considered a one family on some city docs. title did find old HPD violations that implied there were apts, and at some point a fire escape was put on the side, so Im guessing it was used for apts. I assumed this was illegal and remembering the city in the 60-70s t wouldnt have surprised me if they got away with a fire escape after all there are still cinder block additions built on public sidewalks left all over brooklyn from that era no one seems to care enough to condemn. The title also turned up an old permit pulled to convert ground and cellar to dr offices that permit was never inspected though that was what they had gone and done i removed that work because I didnt want drs offices and wouldnt have gotten a loan that way and most important it would never have passed an inspection which the city insisted be done either to sign off on the drs office or confirm my assertion the plan was never executed. during all this i made several attempts to find what information DOB had on the building and as far as I could tell only the few dob and hpd violations mentioned some of which were open and i had to cure.

It now occurs to me perhaps these apt were not quite illegal and i might have a shot at getting a two family Cof O without what? I guess the question is what would be required to make a case for this that would stick? and what work or tax consequences would that trgger? and would there be some difference between that two family and one where i went and did all their sprinkler fire escape etc nonsense?