Floor plan of a multigenerational house

But you are talking about an option. I assume the family is growing. But initially, the plan is for 3 bedrooms with a small living room. Isn’t it usual to start with fewer bedrooms and then use the attic if the family needs more bedrooms? For me, the explanations are not sufficient, so I’m out for now.

Originally, there were 2 bedrooms planned (Schlafen 1 and Schlafen 3), an office / storage room (Schlafen 2), and a living-dining room with open kitchen.

Meanwhile, I also see that the living-dining room with open kitchen is probably a bit tight. Therefore, it will probably be better to do without the office storage room (Schlafen 2) and use it as the second bedroom (instead of Schlafen 3). Schlafen 3 could then become the living room.

As I said, we are still in the planning phase.

It is better to be in planning than finished.

... Grundriss vom Architekten...

I don't see that anywhere. Also, the question of whether the height of the attic floor is sufficient at the stairwell would be visible in the cross-section from an architect. What you have there is not really a house design. Besides, in my opinion, there is a lot that is thoughtless — in a phase of an already existing plan from an architect, very questionable...

It would not be a problem if there were no architect at the moment — however, I would advise you to consult one who has experience with two-family houses.

If your property is 18 m wide - you must stay 4 meters away from SW. This leaves 14 meters. Then you plan a house of about 10 m - leaving 4 meters. You can no longer fit the garage of 7x7 meters in the SO,... Or do you move your house 7 meters to the north? Is that within the building window? Is the garage then "in front of the house," directly adjacent or further to the south? Then you basically have to go around it to get to the entrance door located on the east?

The north arrow, the location on the property, and a section or indication of the roof pitch etc. are missing. Otherwise, nothing can be assessed at all.

... so far only the north arrow has been provided.

... so far only the north arrow has been supplied.

Roof pitch is max. 35° (by the way, I had already supplied this above)