well, for one thing, you need to deactivate all morphs except the ones you want in the Full-Body Morph (FBM). The reason is that the FBM encompasses every dial that isn't set to 0. For instance, Mike's head has a "Michael" dial which is set to 1 by default. If it's set to 1 when you make the FBM, then the FBM will include that dial. So if the "Michael" dial is still set to 1, and you set the FBM dial to 1, then the "Michael" dial is applied TWICE. That could be what's affecting the jaw. As for the rest of the body, I'm not sure. What morphs were you trying to combine?