Hello Dear Client!
I have done quite a huge work and have looked at various concepts. Finally, I've come up with two options which are designed to minimize cost of reconstruction and maximize comfort and energy saving.
First floor both of two options is divided into two apartments because having only one flat on the First floor requires demolition of the staircase and construction of another one, which will be too expensive and difficult.
Second floor is different. The first option consists of two apartments and the second one is just one big apartment. So in total, the first option is four apartments plan and the second is three apartments plan. Actually I recommend you to choose four apartments because of these reasons:
-four apartments reconstruction costs less than three apartments
-In three apartment option, big flat on the first floor can be too big for potential lodger so it can remain empty
-renting 4 small apartments will bring more income than 2 small and 1 large apartment.
Whatever you chose, I've uploaded two completed plans for you.
Third floor was left untouched. But now it can be collective space for the residents of the house (make a small library, mini bar, or just a sofa and a coffee table) or it can be your own room to keep your staff.


__________________________________________________Three apartments plan_______________________________________________________
First floor:
-Bathrooms are situated in such way to make it comfortable when you enter the apartment and want to wash your hands
-Closet niche in the apartment on the right isn't necessary, so you can just not do it and move closet to another place
Second floor:
-Bathrooms are situated in such way to make it comfortable when you enter the apartment and want to wash your hands
-Plus there is a separate bathroom for the master-bedroom
-Central hallway size can be reduced by enlarging of two bedrooms if you want

__________________________________________________Four apartments plan________________________________________________________
First floor:
-Bathrooms are situated in such way to make it comfortable when you enter the apartment and want to wash your hands
-Closet niche in the apartment on the right isn't necessary, so you can just not do it and move closet to another place
Second floor:
-Bathrooms are situated in such way to make it comfortable when you enter the apartment and want to wash your hands
-Closet niche in the apartment on the right isn't necessary, so you can just not do it and move closet to another place
-Every apartment on the first floor has its own balcony