UV Sculpt: How to limit effect to selected verts?

Hi all. New to blender since 2.8, coming from other 3d applications (modo / maya / zbrush). I’m using UV sculpting tools today (relax / grab) and want to be able to only have these tools affect selected verts, edges or faces but no matter what I select the tool grabs ALL verts - even unselected ones. I am trying to spot-relax certain portions of my uv map. Pinning doesn’t seem to work. The only thing that works is ‘lock borders’ but I’d like to be able to lock more than borders. Is there any way to do this? Thanks!

Facepalm update: Realized I can just hide the polys that I want unaffected…