The main challenge in this contest is privacy of each apartments. I think this the best possible layout of floor plans especially in upper floors.
In upper floors, The proposal has designed according to the height difference between floor level codes of each rooms.
In this way, I have followed these goals:

- Attention to privacy of the units
- Separate access for each units.
- less demolitions = lower cost
- Using internal stairs in place of external stairs
- Placing the wet zones (kitchen, bath) near the current water drains.

If you like the design yet need some changes, I would be happy to help you!