Floor plan design for a semi-detached house 17x10m - Best space utilization?

So, it's about a two-family house - vertical, so as not to have the tenant above you, that's okay; but it is an undivided plot.

Against this background, it seems to me a mistake in thinking,
- 1) to split the units 50/50;
- 2) to let the dividing line run so straight and parallel to the outer edges, as if it were on a boundary;
- 3) because you want a straight staircase yourself, to also provide one in the tenant's half.

In view of the entrance-side situation, I find the height gradation better than piling up for level equality. Would the permitted ridge direction possibly allow building shed roofs (with skylights for the higher one, but only if it remains on a joint plot)?

Besides, unsolicited advice can also be worth considering - this seems to apply to the doubts about the brilliance of the financing.

We are also glad that we are out of the terraced house. On the left, 2 small children, on the right, 2 small children, 2 more 2 small children. Basically, we couldn't sit in the "Gärtchen" on Saturdays and Sundays. It was simply too loud. One neighbor had also put something like a treehouse on the border for amusement. Such fun...

Left 2 small children, right 2 small children, another 2 small children. [...] One neighbor had also placed a kind of treehouse on the border for amusement. Such fun...

Although I am already among the Riester generations, I still like children. They are not all terrorists; on my street they are even mostly well-behaved.

It's a bit off-topic, but the children were all very well-behaved with us too. Only 6 all together right by the fence in a garden of 50m² - we were just inside the house every weekend. Without children, you basically shouldn't move into such a settlement. My mistake.

I also belong to the Riester generations, but I still think children are good. They are not all terrorists, in my street they are even predominantly well-behaved.

But not 7 children in 42 sqm.
And there will definitely be visitors.

And since OP is planning to have one child and possibly will need some space for their own family, I would advise not to rent out to more people than you are yourself. You can quickly start feeling uncomfortable.

I would advise against renting to more people than you are yourself. You can quickly start feeling uncomfortable.

Also for that reason, the suggestion is not to design the rental unit to be the same size.