Ideas for floor plan adjustment of house with extension on the west slope

I am looking for ideas for the floor plan adjustment. The house is located on a steep west-facing slope and dates from 1955. We would like to renovate the house so that two separate apartments are created. We would like to use the apartment on the ground floor ourselves with two people. The kitchen can be open. Additionally, an office would be nice. Who has ideas for the renovation and floor plan redesign? Unfortunately, we are somewhat at a loss and do not know how the extension towards the east can be used, redesigned, or adjusted most effectively with the tiny little children's room, or how the hallway area could possibly be optimized? Many thanks in advance for ideas and advice.

Please answer the attached questionnaire - it would be important to know whether you want to stay as a couple or if you are planning to have children, etc.

It would also be important to know whether you want a complete renovation or only want to change interior walls. Should all the electrical and plumbing be redone? Then you have more options than if everything is to remain as it is. And and and... a few more details would be necessary. Is the facade allowed to be changed? Nowadays, there are indeed buildings from that period that are already under [Denkmalschutz], etc.

Unfortunately, I did not find an attached questionnaire. We definitely want to stay as a couple and do not plan to have any more children. During the holidays, our daughter is occasionally here for a few nights, but so far we have managed that in our 2-room apartment as well. We definitely want to carry out a complete renovation. The electrical and sanitary installations will be redone. The house is not under monument protection. However, we want to limit exterior changes to expanding windows as much as possible. What other questions are there?

Building fabric, insulation standard, windows, etc. all from 1955? If possible, please upload photos of the property. Concrete or wooden beam ceiling between the ground floor and first floor? Your apartment must be separated/lockable from the stairwell?

The fireplace prevents the desired open kitchen, the small children's room would be the only passage to the extension due to the future "public" hallway, resulting in a narrow living room. How should it be insulated? The first floor lacks a bathroom, kitchen, and storage room to be usable as a separate apartment. If you retrofit these, a two-room apartment remains; is there even demand for that in your single-family home area? As a rule: small two-room apartments are centrally located in the city for singles and couples, with barrier-free accessibility also for retirees. Outside the city, families with children prefer to live, but then at least in four- or five-room apartments.

Therefore: none of your wishes can be reasonably implemented in the house: with the planned renovation, nothing but the bare shell remains, so demolition + new construction can be considered right away. It will be minimally more expensive but tailored to needs.

Thank you for the detailed response. Everything from 1955. Unfortunately, I currently have no way to take photos. Between the ground floor and the upper floor there is a wooden beam ceiling. Lockability from the staircase to the apartment would be very convenient for us. We are still uncertain about the insulation. There is definitely a very high demand for a two-room apartment here. However, the house is situated in such a way that barrier-free access would not be possible at all. Possibly the storage room and the WC on the upper floor could be combined into a shower bathroom. Demolition and new construction are definitely out of the question. However, we do not know what renovation costs would be incurred.

We would like to convert the house so that two separate apartments are created. We would like to use the apartment on the ground floor ourselves with two people.

An extension is to be built on the ground floor, which offers about the same or less space than the attic, which someone would then want to use, who would have to walk through the ground floor apartment to get there. That sounds to me more like nonsense than a plan (???)