Roof heightening / extension / annex - cost estimation

Hello everyone,
first of all, thank you for your quick responses.
Regarding the heating, underfloor heating should be installed upstairs. The bathrooms on the upper floor above the bathrooms on the ground floor.
The thing with the "second apartment" is initially uninteresting, we would basically live under one roof with my grandmother (in need of care), with a small extension and front door to at least give the impression that everyone has their own apartment. The biggest question mark for us is really the attic conversion.
So raising the knee wall and conversion. Of course, the prices can vary significantly due to materials and interior, I’ll say right away it doesn’t have to be a golden toilet we just want to be able to live reasonably and still have many years to beautify the whole thing.

So raising the knee wall and extension.

As I said, show the original object.

we would basically live under one roof with my grandma (in need of care),

Oh, and the whole fun also minimally invasive, because grandma is living in the said house during the construction?

The grandmother could move in with the thread creator during the construction period, or into one of the other two houses on the property. Would that be a problem for any of the parties involved?