generate full surface files from one selected scout (from another surface)?
Is it the menu Scout > Edit surface > Keep only selected scouts you are looking for?
https://neuroimage.usc.edu/brainstorm/Tutorials/LabelFreeSurfer#Subcortical_structures:_aseg_atlas
This done in this function:
brainstorm3/toolbox/gui/panel_scout.m at master · brainstorm-tools/brainstorm3 · GitHub
dilate the new surface (probably via creating a surface mask 1st, prior to tess_envelope dilate step). Step 1 optional if one could dilate a surface scout (I am thinking more about closed surfaces, such as hippocampi).
What do you mean with "dilating"?
You want to create a new surface larger than the previous one? By moving the vertices a few millimeters away from the center of mass along the normal to the surface?
This is a very tricky problem for non-convex elements, as it may quickly cause self-intersections...