Final floor plan planning - Rose-colored glasses

Throw out the third bathroom. You don't have that much space. Use the planner from Villeroy Boch. At least it has realistic dimensions. Use your current bathroom as a reference for spacing. Put the washing machine in the third bathroom and the second bathroom is just a bathroom, not a combined room. Better to look at the toilet than to climb over it.

Thanks for the tip with Boch. Maybe I'm a bit slow on understanding what you mean. 1st bathroom - parents' bathroom 2nd bathroom - children's bathroom (only shower, washbasin, and washing machine) 3rd toilet (WC and urinal) So actually only 2 bathrooms. Which one do you mean by the third bathroom? You're right about climbing over it. I had no feel for that.

Children's bathroom without a toilet? That is now so absurd to me that I thought you hadn't marked it. Honestly, I would prefer toilet and shower together and laundry separate.

ps.: should there be a note on this - yes, I also posted the floor plan in another forum

I already saw it last night. There, unlike here, you would even be allowed to refer to the crosspost with a link - but probably only those who already recognize it themselves would notice anyway. In terms of content, I agree with here (and otherwise I repeat my ceterum censeo, you should, at the risk of having your wild ideas talked out of you, let professionals handle it).

What about the drainage actually? Not much is supposed to be changed below.

How does the drainage actually look? Not much is supposed to be changed downstairs

The connections work out

I still find it monstrous. It destroys the apartment on the ground floor and upstairs it's a bad compromise.

You don't always have to, under any circumstances!
This is really one of those cases where I can't find anything good, even with a lot of understanding.

As I said, I would wait to see what time brings before spending money on something like this.

The totally built-up result will never be sold well again.