Neighbor wants to fill up on the slope - what to do?

Hello dear forum, we are located in the state of Bavaria. Our neighbor informed us that he wants to submit his building applications for a single-family house with [CP] as part of the exemption procedure. He plans construction with a slab foundation, we with a basement. Our properties are on a slope. The municipality's development plan stipulates that no changes to the terrain surface are allowed along the property boundaries to the neighbor. Edge development for [CP] / garage is permitted. The neighbor now wants to design his driveway including carport at ground level. That means he wants to level the ground over a length of 13 meters. He leaves about 50 cm space to our property. According to my calculation, he would level up about 1 meter (from the start of the street to the end of the [CP]). We ourselves do not yet know if we might place our parking spaces next to his [CP]. That means we do not even know if we would level up anything. 1. Is he allowed to do that within the exemption procedure, e.g. with L-shaped stones? 2. What risks could arise for us as neighbors? (Drainage / problems during rain) 3. He wants us to sign his submission plan, which we do not want to do without consulting our construction company / district office first. Sensible? I hope you can provide some input for the conversation with him. Are there any experiences and what should we ask or clarify with him in the conversation? Many thanks. Best regards Tobias

2. What dangers can arise for us as neighbors? (Drainage / problems during rain) 3. He wants us to sign his submission plan, which we do not want to do without consulting our construction company / district office first. Sensible?

2. He must drain onto his own property; how he does that is his business.

3. It is always sensible NOT to sign anything if you do not know the consequences exactly, yes.

Others know more about the content.

We ourselves do not yet know whether we will perhaps place our parking spaces next to his CP.

Quickly think about how you want to implement this. Wouldn't a mirrored execution also make sense for you? Then you both adjust slightly and everything will fit perfectly.

If he moves in 50 cm from the boundary, he is allowed to do that. I believe up to 2 m is permitted without approval.

Of course, it would make sense if you do it together, then the neighbor saves, for example, the L-bricks and you have something in his favor!
Besides, you can both build right up to the boundary!