How to change the floor plan?

What is supposed to be greedy or childish about that?
Just for the bedding alone, we need a 2-3m wardrobe

Yes, but a wardrobe for bedding has no place in a dressing room. Don't you have a basement anyway?
Just like a washing machine upstairs would annoy me a lot. If there really is an emergency and someone urgently needs an article of clothing, and you have to run the washing machine late at night, then everyone benefits from that [emoji85]
I just don't understand why your wife values the washing machine and your wardrobes including bedding more than giving the children more space. You treat yourselves to it too.

What I miss on the ground floor is a storage room. Was a utility room ever planned anywhere, apart from the bathroom and the basement? I'm asking quite specifically, where is the usual stuff (bottles, waste separation, stroller, bucket, vacuum cleaner, broom, etc.) supposed to be?

Attached are the corrected room sizes for upstairs. They have shrunk a bit - I made the hallway a little more appealing.

Yes, you are right, maybe it's better to accept that 1 child - maybe the smallest one - only gets a small room with 13.8 m². The others then get 2 almost equally sized rooms. Unfortunately, the square meters are not correct here. It is a program error that does not subtract the wall thickness. You always have to deduct about 13%. Well, but it's not really perfect either. But maybe you can gather ideas and then brainstorm with the architect.

I think the layout is great. Especially since both bathrooms can also be used by the children

On the ground floor, with good will, you could put a 2x2x0.6m (H/W/D) closet in the wardrobe. Vacuum cleaners and brooms could fit on one side. We saw that in a holiday home. It was practical. But there is less space left for the children's things - of course.

If it were my place, I would definitely put the kitchen on the ground floor by the terrace. The path from the entrance to the kitchen would be longer because of that, but it would be worth it to me. I also couldn't do without a pantry. Since there is no utility room downstairs, there absolutely has to be a huge Pax in the study. That's where I put my vacuum cleaner, etc. The sofa for guests is a pull-out. Otherwise, my desk with PC would be there.

In the beautiful window corner in the living room, which is almost like a conservatory, there would be a cozy seating area. You can wonderfully read books there and occasionally look up to watch the children in the garden (whom I don't have). The doors to the hallway should be glass doors so that even more light can come in.

Well, once you have the plan on the computer, you just let your mind wander...

So that the small hallway does not become too dark, I will install 2 small (you can also take a larger one) frosted glass windows with a nice pattern in the interior wall. Ok, now she’s completely losing it... I know.