Ah Ok I guess I have to read 218 pages to understand your insiders
Summary: owns one of the two end houses in a row, where the plots were, humorously like yours, left to scatter planning, and as the last to build is the middle house owner (so comparable to your situation). However, his neighbor middle house owner is the born winner of complete idiot contests, like only Tom Gerhards or Rowan Atkinson could portray in a film. Therefore, knows in the form of the main contractor (GU) this neighbor as a suitable contractor for such a daring operation (said neighbor is building with a basement, thus deeper than the neighboring existing buildings), and all that still in "your" federal state. Unlike me, he himself knows how close his Schilda is to your construction site and apparently considers this main contractor therefore suitable to build your house as well.