Fix orientations of particles in heterogeneous refinement?

Hi all,

Is there any parameter (or if not would it be possible to add such) that one can use to turn off alignment (fix orientations) of particles during heterogeneous refinement?

That it, to skip alignments and just perform classification and iterative recalculation of volumes.

In my experience using RELION, this can be a very effective procedure for removing bad particles, particularly when the particle of interest is very small (<150kDa).