Or the original poster only signs the acknowledgment of the construction plans for subsequent legalization. This does not encumber their own property; the original poster thereby only expresses that the construction to be legalized does not bother them. This signature then opens up the possibility for the district office to grant the neighbor a variance according to Art. 63, BayBO. There are then no building restrictions or loss of value. Whether one is willing to do this for good neighborly relations or for a handful of dollars is something everyone must weigh for themselves.
That would probably be the original poster’s preference. Would this mean that they basically only declared themselves not aggrieved in terms of neighbor protection (which made it easier for the district office to refrain from ordering a demolition); and a declaration to assume setback lines could not yet be “extracted” from this, but would first require further active participation (in the form of a notarized statement)?
If the relationship was good, and it did not disadvantage you, then sign.
De-escalation is all well and good, but pacifism can also “hit” the wrong person:
Basically unpleasant, I wouldn’t accuse the former owner of anything, maybe he didn’t know either.
Given the general depth of German regulation, I consider it almost impossible for someone to engage in unauthorized construction without criminal intent.
You could of course also add the creation of a new driveway to your wish list for the neighbor in my version.... and your property would not have to become smaller because of this, as already mentioned.
I do not yet follow your reasoning here (not out of disagreement, but due to lack of understanding).