Montage and landmarks with mne-bids


I am trying to figure out how to properly store our EEG data in BIDS using mne-bids.
We have data collected using an Easycap in standard 10-20 and fiducials (LPA, RPA, nasion) marked with Localite.

What I have done so far is add a montage to the dataset with


This results in ‘electrodes.tsv’ and ‘coordsystem.json’ in “space-CapTrak” (I guess this is ok?).
My question is how to properly document the fiducials in mri coordinates? Should I

  1. Transform the coordinates to the subjects MRI space and store them instead
  2. Update the fiducial coordinates stored in ‘…coordsystem.json’ to the ones from localite
  3. Add the fiducials to the T1w sidecar and leave ‘coordsystem.json/electrodes.tsv’ as they are now
  4. Something else

Thank you for any input on this!