Floor plan for a multi-generational house on a demanding plot

Isn't the sentence quite complete? Do you notice something / Do you like something or is this supposed to be a suggestion? ;-)

"A," I first think of a staggered asymmetrical semi-detached house. So, a suggestion.

Basically, no parking space is required for the granny flat.

Says who? The building regulations of NRW state that one parking space is required per residential unit. I think an architect will already be indispensable during the planning phase here.

Who says?
The building regulations of NRW state that one parking space per dwelling unit is required.

Yes, that is correct. In my list, I come to 3 parking spaces. What I wanted to express is: The granny flat does not require an additional parking space. Whether all three parking spaces are used by one dwelling unit or not should not matter, provided they can be accessed independently of each other.

I suppose an architect will already be indispensable in the planning phase.

Yes, definitely. With my plans, I primarily want to get a feel for whether it is possible on the property and which floor plan for the dwelling unit is feasible. Based on that, a decision will be made later on whether a granny flat will be built at all. If the desired parameters cannot be implemented satisfactorily, it does not make sense to build a granny flat.
Certainly, an architect is helpful, but if you then decide to go with just the single-family house, it is a shame about the money.

It would be even more unfortunate to now assume the wrong premises and later find out that the project cannot be implemented as planned. Go to an architect or a good [GÜ]. He can create a competent and feasible plan for you for a very low four-figure amount, which you need anyway. Nothing else will help you, not even the opinions of the members involved here.

The statement is clear. Do you generally refrain from doing your own planning or do you see no other option here?

The headline contains a signal term ("demanding plot") for the decided advisability of employing the services of an architect instead of settling for those of a draftsperson. But just as a draftsperson benefits from a client’s template, the anchoring effect of such priming is equally harmful for designing with an architect.

Unfortunately, I’m currently still missing the development plan.

The absence of this basis is exactly the sand on which one builds a calculation without the host. So get it quickly.