Floor plan design for a single-family house with a conversion option to a multi-generational house

I still don’t quite understand - the 1st floor should be a fully functional, independent living area and the ground floor as well? So where are the kitchen and living room supposed to be on the 1st floor?

And why should it become more compact?

Currently, it is designed as a single-family house on 2 levels. With the option to separate the floors. Then on the 1st floor, the master bedroom and one child's room become the kitchen and living/dining area. The 2nd child's room becomes the bedroom, and the "playroom" becomes the child's room or office.

Is a [Mehrfamilienhaus] or a [Einfamilienhaus] being planned?

Sounds somehow like another attempt to grab KfW funding by pretending to create living space.

Sounds like wanting to live on one level in old age because the house otherwise becomes too big. Some posts are somehow strange.. I expected a bit more depth from a house-building forum.