You can use either UVMapper or Compose to create a unified figure that actually joins the obj groups together to stop the separation you've mentioned. The best bit is that the maps are saved so the process is reversible if you wish to use the dynamically modified mesh as a morph for the conforming figure, at least when using Compose, not so strong on UVMapper usage.

EnglishBob's website hosts Compose,  a Java app, and UVMapper is available at www.uvmapper.com/

Like you I've had issues with the weld option, sometimes it works...other times.....well.:glare: