Boundary construction roof terrace on garage

Our neighbors and we have not even started building yet and there are already the first difficulties.
We are currently in the approval process because we do not comply with our narrowly cut building window and the future terrace ends 1m outside of it; otherwise, it would only be 1.5m wide. Our construction company has ideally already clarified this exception permit in advance with the district office and received approval there.
Now, an employee at the building authority recommended that we notify the neighbors ourselves and obtain the signatures ourselves in order to save money. 2 out of 3 agree, as we are moving within our own garden; only the last neighbor is being difficult and feels his privacy is being restricted.
After they spoke with their architect, they suggested to us that they would sign everything and, in return, we sign for them so that they are allowed to build a roof terrace over the entire area of their double garage, which stands on the boundary, and want to undercut the minimum distance of 2.5m. Otherwise, there is no signature.
We have now decided to involve the building authority and have them obtain the signature themselves. We'll just pay a little more, but whatever.

Now my question: Are there any exception permits that would allow something like this? Leaving the blackmail aside, everyone here knows about it.

Is it only about the terrace? Or also about the house? I would have included the terrace with the 1.5m in the plans and then built 2.5m. After that, no one would have said a word.

and received the ok there.

What does "the ok" look like? Was there a formal exemption application that was then approved? Or just the verbal assurance?

We'll just pay a bit more, but whatever.

Well, it only doesn't matter if you received the above-mentioned positive decision and the neighbors do not act. As I know it, the neighbors are informed about your building application and then have four weeks to raise objections. I consider it very unlikely that the building boundary has neighbor-protective effect (Higher Administrative Court Lüneburg of 31.10.2007, 1 ME 277/07: ... The determination of a rear building boundary only has neighbor-protective effect if this corresponds to the will of the planning authority.) - unlike the distance area that a roof terrace would trigger - , but it is not excluded (search engine: neighbor protection building boundary). Therefore, unpleasant delays can certainly occur.

Are there any special permits that allow something like this?

I didn't understand what you want to know.

What does "the ok" look like? Was there a formal exemption request that was then approved? Or just the verbal assurance?

Our architect initiated that. I don't know any more about it. That’s how it sounds to me. I haven’t received any document or anything like that. I was only told that if the request had been denied, we would have planned differently.

I didn’t understand what you want to know.

Is there any loophole through which the minimum clearance distance of 2.5m does not have to be maintained?

Is it only about the terrace? Or also about the house? I would have included the terrace with the 1.5m in the plans and then built 2.5m. After that, nobody would have said a word.

Only about the terrace/balcony. Due to the terrain characteristics, it is considered a balcony (concrete slab with steel supports), otherwise we would have had to fill almost 2m. If it had only been a terrace, we would have done it the same way; that was also advised to us by the architect.

Only about the terrace/balcony. Due to the terrain characteristics, it is a balcony (concrete slab with steel supports); otherwise, we would have had to fill nearly 2 meters.

That means it is about a "structure" of 2 meters height (at the highest point), which is to be built outside the building boundary.
In contrast to a flat terrace on level ground, I can imagine an impairment for the neighbors, e.g. their view past your building.
Does the roof terrace on the garage bother you? Can the neighbors then look into any part of your property where they otherwise cannot? If it doesn't bother you significantly, it could be a deal to alternate later between grilling on the roof terrace or your balcony.