one family to three egress

Its a three over cellar 1 family, would like to convert to 3 family and add a penthouse addition with setback deck on roof.
Confused about egress. All floors have access to the staircase out. the ground and cellar floors also have doors to back yard. I would like to continue the staircase to roof INSIDE the top floor/ apt, it only has a roof hatch. This stair would end inside the addition which would have a door to the set back deck, which I believe the fdny would require a ladder from deck to addition roof. The original stair would be enclosed in 2hr rated halls and i gather sprinklers are require now for everything.

My question is I have a fire escape now on the side ( I have a driveway) if this firescape was approved to continue up to pick up the addition and additions roof then all floors/ apts would have at least two egress and at least one access to roofs from fire escape. is that sufficient?
If so I would actually prefer to remove this fire escape and instead build a four story balcony that could have a fire escape legal ladder from floor to floor it would be b igger better than a fire escape but is there a rule against dual use if all the fire escape regulations are kept regarding clearances etc?

PS anyone know if they are going to approve the pex sprinklers anytime soon.