ᐅ Zoning plan requires a single-story house – suitable for two families?

Hello, I am planning to renovate my parents’ house to fully utilize the existing building envelope. According to the development plan, only a single storey is permitted here.
Is it even legally possible to accommodate two separate households in a single-storey house (ground floor + attic)?
I am planning to have my mother live on the ground floor and my family in the attic.

Thanks in advance.

The ground floor and the attic floor are still two separate stories...

No, the attic is not considered a full story...

As mentioned, my main concern is the legal question of whether two households are allowed to live in a single-story house.

The number of permitted residential units should be specified in the development plan.
Having the mother on the ground floor and the family in the smaller attic sounds moderately reasonable for now.

Yes, it specifies independently of the number of floors in the development plan whether two residential units are allowed to be built.

Hm, I can’t find anything about the number of residential units in the development plan. Does this mean it’s probably not an issue if I plan for 2 apartments in the house?