Reconstruction by neighbors along the property boundary

So: if a building application was submitted for the new/replacement construction of the neighbor, then you should have received a notification from the municipality with an objection period, etc.

No matter when the lawyer appointment is. Contact the municipality today and clarify the question of the building application as well as the question of easements at the land registry office.

A lawyer also needs the land register excerpts, etc. in order to be able to make a qualified statement on the matter.

A burden is always registered on the servient property. So not on the one who builds on the boundary, but on the one who allows it (servient property).

Exactly. The building neighbor is servient – that’s all I wrote.

She is in the right because nothing binding exists orally and she insists on her property rights.

That is to be checked. Just because it is my property doesn’t mean I can do everything.

I have the floor plans from our community building authority. Sorry, I don’t quite understand why to go there again or do you mean because of the new/addition?

Because you should inquire about something. And not the site plan, but the situation in the conversation.

Why does she have to keep the boundary free? Allegedly, for example, one is allowed to build “garden sheds” up to the property boundary and even 3 meters high?

But possibly or probably not, if you significantly affect the neighbor with it. Otherwise, a building encumbrance would be practically unnecessary.
No one here knows if you have a development plan. Probably it is a §34 area. Your house is close enough to suspect a building encumbrance. No one knows your former purchase contract, where something about it might be regulated. All are just assumptions. And that should be inquired by you as the affected person or of course your mother as the owner of the property. And if not at the building authority, then where else? Legal advice is also okay, but even they must examine the “file situation” to determine what the neighbor is allowed to do and what not.

Exactly. The building neighbor is servile - I wrote nothing else.

Sorry, then I misunderstood. I would be interested in a photo.

I would be interested in a photo.

Me too. When you look at the site plan, you can see parcels but not streets, access paths, etc. That might not be necessary here, but everything could somehow be better assigned. Based on the site plan, you hardly have any property. You therefore wonder how the ownership relations are even regulated. Possibly ideal? It is indeed a very large house on very small land.

Above all, from a fire protection perspective, I now view it critically.

Good day everyone and thank you for providing so much information here.

I have uploaded another picture with the main street, side street, etc.

Now so much has come together and such a lively discussion on such a complex topic that I would like to ask again for the sake of accuracy:
What do you think, should we bring all information about the lawyer?
Should we obtain other documents from the municipality or the building authority beforehand, besides the current floor plan?

We have not received a building application from the neighbor or the municipality because the neighbor believes based on her measurements that the construction does not exceed 50m³ and that in Bavaria a building permit is only required from 75m³.
My mother has the purchase contract; we needed it when we had to deal with the new property tax calculation a year ago.
I told my mother that I read on the internet that oral agreements between private individuals can be legally binding and that the neighbor could literally "build" on that, but on the other hand I also read that neighborhood agreements are not legally binding.
Although my mother and the neighbor verbally agreed in my presence, namely: gutter on our property in exchange for cutting the hedge by us several times, they have not yet discussed measurements and dimensions, such as how high, how wide, how long.

Personally, I want to talk to the neighbor again and ask for a construction suspension until next next Thursday, until we have more information from the lawyer, and hope for her understanding (which I think I can persuade her to do, but it is unclear), but I would not know what we could do if the neighbor says: No, I will continue building on Friday. Should we then go to the municipality and the local building authority tomorrow and present the case there, which we would of course inform her about?
What do you think?