Preliminary building request positive - building permit denied

Make an offer to the neighbor for the easement. But actually, that is not your problem. The seller is obligated to fulfill the contract.

Set a deadline for the seller, with a warning of contract rescission. Claim damages for costs.

Why do you have a lawyer?

That is actually the second problem. Together with the plot, we bought a share in the aforementioned private road. Unfortunately, the sewer pipe lies about a hand’s breadth too far on the other side of the road, so we do not have a share of it from the parcel. Accordingly, an easement must be registered for the other property (as required by the city). Unfortunately, our neighbors (as explained in the other topic) are not very enthusiastic about construction on the street, so we assume that we will not get this easement.

??? Swabian railway / Bohemian villages ... I will try a summary of the confusion that I at least hope to have understood moderately well: 1. So you have (from the same seller?) purchased, together with the captured building plot, a share in a property called a “private road,” which allows you pedestrian and vehicular access to your property from a public road. 2. however, this “private road” is only suitable with respect to the right of way for walking and driving to serve the development of your building plot. 3. Regarding the easement with a right of line installation, however, this “private road” is not suitable, since the line-based development does not occur via this path property nor via a public road, but rather the public supply lines lie on the neighboring parcel of an uninvolved party (this is where my understanding unfortunately ends).

Shitty situation, yes. We just don’t know how else we could have secured ourselves in advance. As said, there was this positive preliminary building inquiry on which we apparently relied too much in this case.

Given the situation described above, I consider a positive decision on the preliminary building inquiry without the corresponding condition of granting the apparently yet non-existent development to be factually erroneous, and the municipality liable under official liability due to your unjustified good faith; however, of course, you would only be entitled to sue if you remain injured parties (i.e., no longer if you rescind the purchase). [Personal opinion of a non-lawyer, not legal advice.] The uninvolved party with the public supply line on their private property, which I do not understand, is currently not approachable for you at all. I see the seller of the building plot property exclusively as the fulfiller of your purchase conditions.

At least visually, you could shed some light on the tangled situation by illustrating the whole mess with an excerpt from the cadastre. So simply show the parcels on a large scale in connection with the nearby public roads known to all.

-The preliminary inquiry was made by the notary/lawyer of our seller. Unfortunately, I cannot reproduce the exact content. I only have the "response" at hand. Namely that a development with a single-family house according to §34(?) neighborhood development is possible.

But you know the wording of the preliminary inquiry or had it available before signing the purchase contract? If not, that would be hardly excusable for stupidity. Because with that you could probably have all questions/points answered for us and yourself.

- But if I do ask in a preliminary inquiry whether I am allowed to build a single-family house there, then the question would be: "What if I want to build a single-family house there? Can I?"

There is a simple answer to a simple question. The more vague the question, the more vague the answer. If you only ask "am I allowed to build a single-family house there according to §34 and the development situation should not be examined," the answer will be simply "yes." In a building preliminary inquiry in Bavaria, for example, you must explicitly state whether the authority should check the development situation or not (it is probably no different in other federal states).
You will never get a "yes, but..." answer to your question.

But if someone tells me beforehand that I can build a house there, then that would be a false statement - because I actually can't, as it is not developable.

Again: If the question of development is excluded and not to be examined, then of course the answer can be "yes." You only get an answer to a question. Actually, YOUR house should have been requested in the preliminary inquiry, with all the details.

Therefore, once again the question: WHAT IS IN THE PRELIMINARY INQUIRY?

Please answer this. Post it here. Get it. But do something.

Otherwise, from my side, the question (even if I suspect the answer), whether
- the purchase price was recklessly already paid in full (one does not usually do that in such a situation)
- what legal consequences were agreed upon (probably no penalties from the seller, right?)

I have the feeling that you were extremely naïve and are now receiving a black eye as a punishment.

Imagine it like this. If you ask: Can I drive a car in Germany? Then the answer can be "Yes." That is not a lie either. That you are only allowed to do so under certain conditions (with a valid driver's license, on public roads only with a registered car with road approval and periodic inspection and at least liability insurance, in urban areas only 50 km/h unless otherwise indicated, and so on and so forth). At the same time, however, it applies: Ignorance of the law does not protect against punishment. It may seem unfair in places, but that is just the way it is.