CFD Online Discussion Forums - Split domain

I have a domain that I would like to be splitted in two parts according to a certain condition.
Therefore, I define two "labelHashSet" containing the corresponding cells and the two parts of the mesh are then extracted by "fvMeshSubset"

Code:

    labelHashSet Set1(Set1Cells);

    labelHashSet Set2(Set2Cells);



    // define condition and insert cells in each of the two sets



    fvMeshSubset subsetter(mesh);

    fvMeshSubset subsetter2(mesh);



    subsetter.setLargeCellSubset(Set1, -1, true);

    subsetter2.setLargeCellSubset(Set2, -1, true);



    subsetter.subMesh().write();

    subsetter2.subMesh().write();

The problem is that I have no control over the write() function directory and therefore the files are overwritten.
I also assume it would not be a good idea to mess with the library file. Any ideas?