Hopefully simple UV mapping question

Let’s say I’ve got a UV-unwrapped base mesh from which I’m creating a dyntopo sculpt. I’m aware that dyntopo strips the UV mapping from the mesh when it subdivides, basically creating “holes” in the UV where the new geometry is. Once the sculpt is done I need to restore those “holes” to something close to the original UV map so the two models can share textures.

Thing is, I know I’ve done this before but it was one of those late-night/early-morning experiments and I can’t remember exactly how I did it, and I don’t have the blend anymore. Googling gets me lots of hits on how to do this with identical-topology meshes, or how to start from a nicely-unwrapped high-poly model and go to a lower-poly version, both of which are useful but not what I’m doing here.

Okay I did finally figure this out (also realized this might have gotten more feedback in the Modeling subforum). If you haven’t changed the mesh too drastically you can use the Data Transfer modifier for face corner/face data and see which settings work best. Again, this works reasonably well if your average normals haven’t diverged too much from the base mesh. For instance, adding surface indentations and bumps to a character body part which didn’t originally have enough geometry to support it seems to work all right. Adding a whole new limb or something would be problematic.