Property division - house sale + house construction on a new plot

One might perhaps register the easements on the new property if the area is only to be used as a garden. But the question remains, who buys a house without land and how does the building authority view the floor area ratio resulting from the plot layout, which is equivalent to full sealing. When I look at the surroundings, it seems that there has been a lack of sensitivity in this regard in the past. Therefore: building inquiry.