Floor plan house with granny flat - improvement suggestions?

I also have to say that I'm slowly getting the feeling that, for example, the very harsh criticism of our floor plan might have been a bit exaggerated here and there.

I do not quite agree with this – 1. We are currently planning to build our house and are (still) not thinking about selling and do not want to either. 2. If the children move out, we could move into the granny flat (then we will probably be at an age where we want to live on the ground floor) and rent our apartment to a family with 2 or 3 children.

Great, this floor plan is my favorite of all. It is compact and prepared for most possible eventualities in the future. However, there are unfortunately two decisive disadvantages that you could not have known. 1. The utility room must be on the ground floor and accessible from the street. This is a requirement from the local utility company because of the cold district heating network. 2. My parents would like to be on the ground floor. They currently live on the first floor and no longer want that. I think that as they get older, even more people will want to live on the ground floor. Other than that, the floor plan is great! What is also good is that the roof of the master bedroom could be used as a roof terrace for the apartment on the first floor.

I would actually be interested in the parents’ opinion. Why do they absolutely have to move in there?

If the building application is submitted today, when would the move-in be? Sometime at the end of next year.
What about the 17-year-old today? Will he stay here or leave for training and only come back sporadically?

What about the brother? Is it foreseeable that he will look for an apartment or does he want to stay in hotel mama?
I don’t want to throw anyone out, but these two persons are the uncertain candidates you worry about now and then hardly move in.
Maybe one room shared by both would be enough for them.

That wasn’t the case. You are just learning now that what you want for your money isn’t feasible. And out of desperation, you’re bringing up the old plans again, when for a brief moment the world seemed okay (which, of course, it wasn’t).

I’d actually be interested in the parents’ opinion. Why do they absolutely have to move in there?

The children will be all gone in about 10 to 12 years. And your parents will then already be deceased or where will they live then?

Unfortunately, I cannot follow you here; I have not taken out old plans, the plans I posted here today are 1:1 identical to the plans for which we received the building permit. They were just created with different software.

We currently live in a multi-family house, where we live on the ground floor and my parents live upstairs. My parents have a strong emotional bond with their grandchildren, and it would be too much for them if, after all the years we have lived together, we were to separate spatially in this phase of life.

The youngest child is 7, and I think it will probably take about 13 more years until they move out. Whether the parents, both or just one, will have passed away in 10-12 years or will continue living in the granny flat, I do not know. And honestly, the parents will die eventually (just like we will), but I do not want to speculate now when that might happen.