The filename of the Paraview multiblock is set to the case name / config filename:

For all other volume outputs, the filename is specified with 'VOLUME_FILENAME' in the config file. See e.g. the Paraview XML filename:

This is counter-intuitive and the user is not able to change the multiblock filename in the config file. Is there a reason behind this or can we align that by using the volume filename for multiblock as well?