Single word (Preferably) for phenomenon when two persons who are at not good terms with each other and involve third person to correspond between them [duplicate]

What is it called (Preferably single word) for phenomenon that is taking place when three parties are involved such that first two persons (Group of people, party or Departments, etc) are at not good terms with each other. And so first party involves you (or your department) as the third person to talk (Converse, correspond) to the second party and vice versa. The question is about what kind of phenomenon is happening between all the three parties and not what the third party party is doing individualistically.

The point of this is to highlight to the management the amount of work that the third party (its department or members of its group) have to undertake is a overburdening our department (third party).

Example: ________ is causing excessive work burnout, disgruntlement, disengagement in our department (within third party) since the XYZ department (first party) is reluctant to correspond with ABC department (Second party) and vice versa. And we (third party) have to pay the price.

Solution 1:

Mediation may be the word you are looking for. However, it implies that the third party is trying to end the existing disagreement.

The mere act of coming between is intermediation.

Another word that comes to mind is intervention. Check out the meaning of intervene. If you opt for this word, make sure the context is clear, as the word has a few meanings.

Personally, I think intermediation works best here. If someone intermediates, they act as an intermediary (a person who passes messages or proposals between two people or groups).