Generate a common source grid for all your subjects, compute sources, and project the maps back to the template space. This is described in this tutorial:
https://neuroimage.usc.edu/brainstorm/Tutorials/CoregisterSubjects#Volume_source_models
Generate a common source grid for all your subjects, compute sources, and project the maps back to the template space. This is described in this tutorial:
https://neuroimage.usc.edu/brainstorm/Tutorials/CoregisterSubjects#Volume_source_models