Legally according to the state building code it is a single-family house with a granny flat, so 2 residential units and 2 required parking spaces. Practically, 3 residential units are possible. If you do it officially, you will of course need an additional parking space later.
However, it may also be that your municipality has its own parking space regulation and more is required, or the development plan specifies something different. As far as I know, we are in BW, so it may also be that even fewer parking spaces are needed since there has been an alternative regulation since 2016. Therefore, don’t just look at the state building code, but the exact requirements for your property are decisive.
If there are 3 residential units, as far as I know, you fall into a different building class. Then you also have to take some additional measures that are not required with 2 residential units.
Will there also be visitor traffic in the club office? If yes, how does the barrier-free access look?
Our project is simply not an off-the-shelf one
And precisely for this reason, you should find a suitable architect for such a project who brings your wishes into a coherent concept. If the general contractor only employs drafting lackeys, they will implement every customer wish, even if it is pointless!
But from what I read in the last page, you still don’t really know what you want. This must be decided once and then develop the house according to the specifications. If these basics change, you often have to start over!