morphing a volumetric subject source space to fsaverage

Dear mne-python,

I am setting up volume source spaces for my study to perform MFT later
on. Furthermore I am aiming for a statistical group study using Spatio
temporal Clustering Test.
On my way of doing this I encountered a big problem.
To get meaningful result from my statistical test I have to morph every
subject to an average subject. I try to morph the volumetric source
space of my subject to fsaverage like it is done in the surface-based
example
http://martinos.org/mne/stable/auto_examples/inverse/plot_morph_data.html’.

I tried to change to source code to make it compatible with a
VolumeSourceEstimation. But I am not succesful with it. (When desired I
can also pass my source code)

Does anyone have any experience in volume-based morphing ?

Greetings,

Daniel van de Velden