Now you (unfortunately) hear from me again. Our beloved great-grandmother passed away some time ago. Slowly, we are starting to feel motivated again to focus on the renovation/refurbishment. The current plan is: Either to convert the existing house (a house with two separate apartments on the ground floor and first floor; attic partly developed, footprint 9x10 meters) into a two-family house OR to demolish and build new. Due to the KFW subsidies for old building renovations per residential unit, it is more likely to be a general renovation with major redesign/alteration/extension. The dream would be to turn the existing house into a semi-detached house with two differently sized halves (one half for grandma, the second half for us as a family of four). This would make everything easier to separate (front door, no shared staircase, garden, etc.). However, this is difficult because of the staircase. Does anyone among you have experience or has already undergone such a conversion or can say if something like this is possible? Currently, we are still wildly pondering and drawing ourselves; an architect has not yet been engaged. Perhaps some of you have recommendations or ideas?