Floor plan of a single-family house with 240m² including a 75m² granny flat and garage

I can partly understand your frustration that some people here devalue and ridicule everything that deviates from their own ideas by default. Unfortunately, I can't give you any input on your floor plan, ...

Honestly, it's like the clueless explaining the world to the ignorant (although I like your note about the budget.) If I understood correctly, the OP only wants to build one floor now and add more later. And then he just takes the roof, throws it away, and builds a new roof? Or does he have everything torn down and rebuilt afterwards? You can do that if money is no issue. But then you could also just build two floors from the start and leave the top unfinished. And for a possible family, where the future wife already has to accept having the mother-in-law as a neighbor, he plans 240 sqm right away, although unfortunately there won't be enough money for that. Should she bring the rest? Well, then I already wish good luck with the partner search. Along with statements like:

Unfortunately, or fortunately, there are no regulations here. I have to prove at least one driveway. Where at least two vehicles can park for the two residential units. ... Since we are planning a single-family house with a granny flat and not a multi-family house, this is irrelevant for us. ... It is a village in the East where there are no requirements and so far everyone has built as they wanted. ... ... and there is no discussion about possible building codes or family planning. .... If someone has a suggestion for the chimney that currently blocks the door on the upper floor, I would be very grateful.

I don't know what's sadder: the plan from #1, the lack of basic construction knowledge, the life planning, or the spelling? To maybe advance the matter a bit, here is my recommendation: either build a one-story house with 2 residential units where the roof could be expandable later, or just build a standard house for a family with a bungalow/annex next to it.

Plan a bungalow with 2 residential units. One for your mother and one for you. If you need more space because a partner is found, you can convert the attic. If the attic then also becomes too small, you can build an extension. The big box has to be maintained. Whether it is empty or not.

Are you sure your municipality does not have a parking space regulation or something similar?

before I build new in the village in MV, I look for vacant existing buildings with 300sqm living space (old school, daycare, post office, farmstead), convert 2 apartments and have a reserve for the future. Is there really nothing?

If I understood correctly, the OP only wants to build one story and add more stories later. And then he just takes the roof, throws it away, and builds a new roof? Or does he have everything demolished and then rebuilt? You can do that if money is no problem. But then you might as well build 2 stories at once and not finish the upper floor.

I must have overlooked such a bold plan. I assumed/am assuming that the huge box as an exterior plastered shell with interior finishing is only to be built on the ground floor and over the Saturdays of several decades also finished upstairs inside (?)

Yes, which ones...? There are thousands and understandably everyone understands something different by it.

Thank you very much for all your comments and now I understand that the introduction here unfortunately was not suitable for me and that is why so many comments missed my question.

If I understood correctly, the OP only wants to build one story and add more later. And then he simply takes the roof, throws it away and builds a new roof? Or does he have everything demolished and then rebuilt? You can do something like that if money is no problem. But then you could just build 2 stories right away and not develop the top one.

That is the plan, but I now understand that no one here can help me without going into further detail and that the topic can be closed here.

As I said, this can be closed now because I will discuss this further with the architect and do not want to waste your time.

That is the plan,

This is not a plan, this is madness. Financially and in terms of planning.