Mesh extraction like Softimage

here's something I miss from Softimage...maybe there's a way to do it in Blender that I don't know about, but I can't find it. Let's say you have an object that you want to take a piece from, but follow the object it came from. As an example, I'll use the polys which represent the eyebrow area of a character. You select the polys in that area and choose "extract mesh". Now you have a new object which will always follow whatever deformation happens to the original. If the character's forehead deforms, the eyebrow will follow. You can also make modeling additions to the new object.

I thought it could done by making a linked duplicate, which would be the equivalent of a clone in Softimage. But if I delete polygons in the linked duplicate, they also delete in the original. I don't think linked duplicates should work that way. I should be able to deform the duplicate in any way without affecting the original. Conversely, Any mods made to the original should affect the duplicate (or clone).

Keeping the eyebrow example in mind, we would create a linked duplicate of the character and delete everything except the eyebrow area. It would follow the original object because it's basically a clone with all of the unneeded polys deleted.