Land division by means of a building application with subsequent demolition

Why not build first, then demolish, and then divide?

The building authority will merely inform you that no illegal condition may arise due to the division, which would be the case with an existing house on both sides of the boundary. Obligation aside. The surveyor could anticipate facts, but ultimately he would be falsifying an official document, which is why I don't believe you'll find one who will do that. But stranger things have happened. If you ask at the building authority, you risk waking sleeping dogs...

Thank you very much for the explanation. I understand that...

Why not build first, demolish, and then divide?

Good question. I thought it was not allowed to have more than one residential building on a plot, and since we want to build two houses, the application without division would be rejected. That would only be possible one after the other. So build a single-family house, demolish, and then a two-family house, which leads to higher costs. (Inflation/increase rate, construction site setups, craftsmen travel, and smaller volume of individual orders, etc.) Am I wrong?

Of course, you can build more than one house on a plot of land .. - ask the building authority; with us, it always worked without any problems. It is even easier with the boundary distances.

An acquaintance told us that we can submit the division as part of the building application for both houses and thus shorten the processing times at the authorities

Building applications are decided by building authorities – partly at the district level, partly at the municipal level; and cadastral matters at surveying offices. In some states, these are also at the local level – but not combined with building in a single office, at most in the same department. Therefore, I do not believe in this shortening of processing times. Both plots with multiple buildings can be developed, and buildings can stand on multiple parcels. Without further information, I see no reason for a plot division within the same ownership (and if we had such, probably only could competently interpret them here). But even for discussion with laypersons, you should also let pictures speak here. Where does the idea of a floor area ratio come from: are we talking about a planned (thus not §34) area, or would we already be scraping the "federal maximum"?

if we had such,

... Escroda would indeed have already gotten in touch. Without a site plan and development plan, the situation is not comprehensible to me. I would have to make a lot of case distinctions only to ultimately not have considered the present constellation.