Floor plan single-family house with separate apartment as a 3-unit house

So far, we have primarily received suggestions for the granny flat (for which we are definitely very grateful!), and we would therefore be happy to see the kitchen proposal from @Ysop*** :) Of course, further feedback on the rest of the plan is also welcome, as long as it does not concern the granny flat. We will look at that separately with my parents as described anyway.

The "problem" is precisely that if you plan an "equal / really nice" second apartment in the house, this affects the entire building. Only if you plan what remains as a second apartment would it be different... but exactly that, I would not find appropriate. To have a nice apartment empty for five years, especially now when your family is still small, does not seem ideal to me either.
For me, the fundamental question would arise much earlier or deeper. Can/will the parents move now? There are certainly ways for that too. Or they build it anticipating their needs and rent it out for 5 years until they move in.
You can always manage a kitchen among other details, for me the basics are still not fitting.

we have consciously decided _against_ a guest room,

That too referred to the parents' apartment and the suggestion from elsewhere to plan separate bedrooms.

Why separate offices? Why not a shared one? The likelihood of a teacher with three children and an IT specialist both being in the office full-time at the same time is rather low. Why not one office with two workstations? Especially if you assume that for the next 10, 15 years a whole wing will still be available as space. You are currently three people and planning 230 sqm of living space. That is already quite substantial.

Of course, further feedback on the rest of the plan is also gladly welcome, as long as it does not concern the granny flat. We will still separately review that with my parents, as described.

But you still haven’t answered my questions either. You apparently only expect cosmetic suggestions for the kitchen, etc., although actually the entire floor plan or the concept of the 3 residential units would need to be changed...

Regarding the granny flat I would not want to move in there. 1. Very cramped - you no longer work, want to pursue your hobbies or simply sleep without your partner snoring. No possibility to get out of each other's way. 2. With limited mobility or help from a care service it no longer fits. Check out Nullbarriere for this HT very very tight. You would not be the first for whom what was planned is not enough. Minimum distances, space for the technician etc Utility room where will laundry be washed, canned goods, tools and decorations be stored? Bedroom downstairs draw a proper bed with frame once. Kitchen is show and not practical. Possibly swap with living area draw furniture everywhere to scale and consider movement spaces e.g. 80 cm table edge wall (minimum)

Why separate offices? Why not a shared one? The likelihood of sitting full-time simultaneously in the office with three children as a teacher and IT professional is rather low. Why not an office with two workstations? Especially if you assume that a whole wing will still be available as space for the next 10, 15 years. You are currently three and planning 230 sqm of living space. That is already a significant amount.

We actually don't need that. One shared office is more than enough. We fully agree with you. But of course, we don’t want to leave the granny flat empty for the time being and would first use it as an office. That’s why, theoretically, we wouldn’t need the actual office on the ground floor (which is currently labeled as "sleeping"). I had the idea of possibly leaving out the wall towards the living area for now and significantly enlarging the living space. If (after the parents move in) the space is needed again as an office, a drywall partition could be inserted.

You still haven't answered my questions either. You apparently only expect cosmetic suggestions for the kitchen etc., although actually the entire floor plan or the concept of the 3 residential units would have to be changed...

Sorry, the answer from was also addressed to you. I forgot to mention you. I had overlooked it due to the number of replies in a short time.