Splitting room in half

[Mina G.]

I have 2 family house the first floor is 2 bedroom the 2nd floor is 3 bedrooms.

I have attached a image of the current setup and what I want to add. Black color = current walls.

Green color = walls I want to add.

one thing I dont know what to do about.

There is a hallway when you enter the apartment. If I add the wall it will be in the middle of the hallway.check the attached. How should the shape of the corner be near the hallway?