bagginsbill: The problem is that I need the normals to match between the skin and the toecaps along the transition line (or better, a transition zone). The easiest way to achieve that for both versions of the mesh simultaneously is to duplicate vertices over a certain range. An alternative I could try is to lift the toecap vertices from the base mesh just enough so that programs like Poser and DAZ Studio recognize them as different, but the normals still match and the displacement is not visible in renders. Another thing I could do is work with the toecaps remove while working on the figure and put them back on for the final version, hoping that other developers will never run into the problems I'm having now.

But to be honest, I am not entirely sure anymore if built-in toecaps are really better than conforming ones. They are certainly better than full conforming stockings, but that's not the alternative I'm suggesting. A conforming figure could inherit all the bend parameters from the base mesh, and I fail to see how it would be trickier to make morphs for two separate meshes than for the exact same geometry baked into one mesh. In fact, I think it would be easier to work on one figure at a time.

Finally, let me just quote something you posted in another thread a few minutes ago: "Look, we can all wish that every possible flaw, every possible thing that is non-optimal, all of it gets fixed all at once." 

-- I'm not mad at you, just Westphalian.