Version 1
In version one, the bathroom closer to the entrance is bulked up in order to get a new storage space which can be used for coats or as pantry. I have moved the bathroom entrance into the corridor a bit, so I got a space for the washing machine and a small closet which is in front of the granny room.
When it comes to the bathroom closer to granny’s bedroom, I have kept the small step and for that reason I have also left the sink at the same position. The reason I kept the existing stairs in the bathroom is that I suppose there are water and sewage pipes below them. Together with sink, there are also bathtub and bidet, as requested. The Grandmother’s bedroom got a walk-in closet placed behind the bed with pocket door at both sides of the bed.
In the middle bedroom, I have placed the desk in front of the window, with a sofa bed. By using the sofa instead of a bed, I have freed up some space so the room can be more functional. There is a walk-in closet built into the wall which separates the middle and the children’s room.
The children’s room which too has a walk-in closet, a bed and a lot of free space that is suitable for playing and eventually for another child’s bed. Children’s room is placed where once used to be the kitchen, which is new moved to the non-enclosed room. Kitchen has a 3.35m wall as requested, where I have placed all the kitchen elements. It also has an island.
Kitchen, dining room and living room make a whole as they are all non-enclose and can be entered from the entrance hallway. The living room has a 2.65m wall, so all the furniture can be kept. The dining table is positioned on the right if entered from the hallway and left if entered from the kitchen. It is positioned there to allow enough space for the table to be set and has enough seats for 10 people.
Version 2
Version two is very similar to the first one, with the difference regarding the kitchen closure. In this version, I have put a glass sliding door between the kitchen and living room with the intention of isolating the kitchen, while still keeping the visual connection of it with the rest of the apartment. The doors can be either opened or closed, optionally without burdening the interior.

NOTE
In neither of the versions did I change anything with the triangle space behind the toilet in the close-to-entrance bathroom, because I have come to conclusion that its use is that of the sewer opening. It is less complicated and all in all better to keep it where it is.