Property purchase - Risk of a "linked transaction"?

That does not exclude the possibility that within the developed building area there is a huge plot of land that is divisible enough to justify a cul-de-sac for its half a dozen parcels after division, but which has not yet been considered by any municipality.

Exactly, that was precisely the situation in our case. But construction started without a building permit, oh how fun (and expensive) that was.

Sounds somehow like someone owns farmland and dreams of becoming rich by selling building plots. And the buyers are supposed to pay for the feasibility.

Hehe, and such birds then like to respond to building land search ads from general contractors and developers. The latter just file it away and forget it, but GCs are happy to jump on it to market it as well. With a preliminary contract, you then trap yourself and may have to accept a "replacement plot" elsewhere because the building readiness of the plot is waiting in cloud cuckoo land and the in-house draftsman has already designed several castles in the air on it. Then we are back to the keyword "11ant short sale" – even if in this variant the bait plot (and even the contact of the seller to the owner) would actually exist for once.

Exactly, that was precisely the constellation in our case. But construction started without a building permit, oh how funny (and expensive) that was

And now you have built on a private road, would have loved to ask the municipality to dedicate it publicly, but for the price expectations of your dear neighbors they didn’t want to, and now you roll your garbage bins a hundred meters to the public road and have the letter f appended to your house number shared with the neighbors?

And now you have built on a private road, you would have loved to ask the municipality to dedicate it as public, but because of the price expectations of your dear neighbors they didn’t want to, and now you roll your garbage bins a hundred meters to the public road and have the suffix f behind your house number shared with the neighbors?

Something like that, yes. Only that we have our own house number. The garbage bins, yes, they have a long way to go. The shared path just became a bit narrow, so no bulky waste collection and such. The fire department can just get through. You had to be very inventive with the parking spaces. Sometimes not as many houses fit on a plot as the property community would have liked. It’s just also annoying when you start building without permission, collect installment payments, and it’s not approved afterwards. Another builder wasn’t so successful, dismantling and building ruin. Since someone else in the village had already created a building ruin, the building authority was a bit sensitive about that.

How many plots of land does that result in, which the GbR is supposed to acquire? If the seller sells it as "one," then the development can only take place afterwards. If the seller has it developed, then he sells x plots of land. This should be reflected in the purchase price.

Whether I would form a GbR with my neighbors, however, is questionable. From the seller's point of view, it can make sense.

Excerpt from Juriforum: The development of a plot of land is the responsibility of the respective municipality according to § 123 Baugesetzbuch, whereby it should be noted that according to § 123 para. 3 Baugesetzbuch there is no legal claim to development, even if a development plan provides for the development.

There is also the possibility of private development, often taken up by developers who acquire a larger plot of land. This means the developer builds a road that connects the individual plots and makes their customers owners of the development road. They are then responsible for everything that otherwise falls within the municipality's area of responsibility, e.g. winter services, traffic safety obligations, maintenance.

Whether I would form a GbR with my neighbors is questionable. From the seller's point of view, it can make sense.

That is exactly it.

There is also the possibility of private development, often used by developers who acquire a larger plot of land. This means the developer builds a road that accesses the individual plots and makes their customers owners of the access road. They are then responsible for everything that would otherwise fall under the municipality's area of responsibility, e.g. winter service, traffic safety obligations, maintenance

That is why it is rather unwise, and by no means the only alternative.