Neighbors Building - Concern of Damage

I am building together, and the neighbor next to me is also building. I requested a permit to add another floor in the stairwell, and it was approved. The engineer's instructions were that the stairwell wall should be made of concrete. The stairwell is between the apartments, so each tenant builds half of the stairwell wall, which also serves as a wall of his apartment. Each has his own contractor. The contractors agreed among themselves to ease the work that the neighbor's contractor would build the block wall dividing the apartments, and my contractor would build the entire stairwell, including the wall separating the stairwell from the neighbor's apartment. This agreement was made between the contractors without my involvement. After the fact, it turned out that my contractor, who poured the stairwell wall also for the neighbor, deviated between 3 cm to 5 cm into the neighbor's apartment space. According to him, the mistake is due to the neighbor having first made columns himself, and only the completion of the wall was done by my contractor, and the deviation is actually already in the columns; he followed the dimensions of the columns. It is impossible to correct this, i.e., to remove from the wall's thickness; the only option is to dismantle the entire staircase to the wall, which costs 50,000. The question is divided here into two parts: A) Is this considered damage caused by me at all, since the neighbor's contractor was supposed to do it, and he agreed with my contractor without consulting me that he would build blocks for him and my contractor would do the stairs, and therefore it is considered that his contractor hired a contractor to do the work for him, and incidentally, he is also my contractor, or is it still considered my business. B) Do I or the contractor have an obligation to repair or compensate for such damage?

Hello,

It is not possible to answer the question in this form. You should jointly approach an agreed-upon judge and present the facts to him as they are, and he will decide.

[There are several issues here that need to be carefully examined before a decision can be made. For example, whether the columns that the neighbor made indeed forced your workers to enter his area. What exactly was the agreement with the contractors regarding the division of work, and more].