If the garage is now also supposed to be partially underground, it will become even more complicated. You will then need a corresponding ramp, for which there is no space either. The whole project is already very, very borderline in many respects. We are talking about a ~380m² plot, which was sold for over 2000€/m², and is to be developed with two semi-detached houses plus 6 parking spaces. Normally, anyone with some knowledge of the matter would say: completely impossible. Is there a positive preliminary building inquiry? I see a lot of trouble coming your way.