Hi Rasheeda,
The models in Brainstorm convert all the EEG/ECOG/sEEG recordings to an average reference, you don’t need to do it explicitly.
If you do want to apply an average reference montage to your recordings, use the process “Standardize > Apply montage”.
To learn how to use the new montage interface, please read the EEG/Epilepsy tutorial.
For questions on OpenMEEG, please contact the OpenMEEG developers:
http://openmeeg.github.io/
Cheers,
Francois