Atlas has this ability, though I don't think anyone has written anything that actually allows it to be done. So basically (and unfortunately), no.
What you can do is create caves using DIFs and use Legacy/Mega Terrains with a hole cut out of the terrain in the Terrain Editor and then use the DIFs as the cave. That's how it's been getting done up to this point.
Torque 3D Owner Ted Southard
What you can do is create caves using DIFs and use Legacy/Mega Terrains with a hole cut out of the terrain in the Terrain Editor and then use the DIFs as the cave. That's how it's been getting done up to this point.