I really appreciate your posts, but this is quite bewildering.
I am sorry if you have taken the figurative use of the "ich sachma" folk song the wrong way. I used this allusion because hopefully everyone (and thus also the original poster) then "has the song in their ear," and thus "the penny drops": namely to consider the phenomenon that in each verse of the construction project song a comrade will drop out for a different reason: one only wanted the plot in the front left and no other, the next not the plot at the cul-de-sac, the third is disgusted by the rolling service for the trash bins all the way to the corner of the public road, and so on. The avatars of these insecure cantonalists in the song are purely symbolically "little negroes," and were never seriously literally "as one would say today, underage persons of color (m/f/d)." By the way, I chose a Yiddish "mammele" and certainly not blue ;-)
In my opinion, the building authority will demand a new partial development plan due to the size of the plot. That will then go through all instances.
I rather don't think so. As I understood the original poster, the plot is in a planned area and will only undergo a rezoning, but will be overlaid with the - unfortunately concealed by the OP - building criteria of the surrounding parcels. The barrel of a special section would probably only be opened if the demand had changed significantly since the latest version of the development plan, for example, if so many semi-detached house applicants were queuing that no more detached single-family houses were to be allowed in this area. We are talking here about three thousand square meters minus street space, so in Mr. Kopper's sense peanuts ;-)