Property purchase - Risk of a "linked transaction"?

For the developer, that is very clever. He gets access to land even though developers at municipal

Dear Wilder Süden, I did not mean you, I just wanted to explain it again for the OP because many do not know what a developer actually is. You are of course right, I only just read that it might come across as misleading.

There is also private development with handover to the municipality after completion.

There is also private development with handover to the municipality after completion.

If the road belongs to a single Snow White, it will proceed sensibly. But not with seven dwarfs, of whom only one needs to believe that the road land is worth gold – then the deal will not go through:

There is also private development with handover to the municipality after completion.

If the municipality feels like taking care of a road it did not want to build... It is of course not to be excluded that the municipality saves money for the development through such constructions (tight budgets are common), but you save even more money if the municipality is not responsible at all but rather the private owners.

Is development via private road really such a taboo?

Not taboo, but it is one of the things you actually want to avoid. Unless you always wanted to buy a quad with a snowplow and have the neighbors pay you for it ;) Usually, people buy something with private development either because they have no idea or because there are not many alternatives due to the scarce plots. No problem. I also find the award conditions with you very exemplary, especially that the house must already be financed.

The property owner, to my understanding, originally made contact with the sales manager/prefabricated house company themselves,

Here is probably where the root of the problem lies. I would be surprised if they don't have a contract with each other. And then it's a tied transaction.

Not taboo, but it’s one of those things you actually want to avoid. Unless you’ve always wanted to buy a quad with a snow plow and get the neighbors to pay you for it ;)
Usually, people buy something with private development because they either have no idea or don’t have many alternatives due to the scarce plots of land.

Yes, developed plots usually cost so much here that in the end you can only put a doghouse on them o_O. If it’s just about riding a quad in the end, I have no problem with that;)

That’s probably where the smelly dog is buried. I would be surprised if they don’t have a contract with each other. And then it’s a linked deal.

Any idea how I could protect myself from that? Does the tax office find out about such arrangements at all, or does it ultimately come down to what is stated in the notary contract?

That may be true that the purpose of the GbR in the partnership agreement is only related to property development and it is even stated that the company dissolves upon completion of the property subdivision (so who is supposed to act as liquidator then?). But as long as the GbR exists, a note will appear in your Schufa / Crefo etc. that you are a partner of this GbR (and whether one of your GbR buddies is listed in the debtor directory). Cheers to that.

As I said, I assume (and will clarify once more) that the GbR will only exist for a short time. And at least at the time of purchase, all buyers must provide proof of financing, right?
Sure, it could all be simpler, but as written above, it’s unfortunately not the case in this region that you could just take the next available plot...