Well after a wasted evening, I am back on track. I spent about two hours last night spinning my wheels --though I have to accept responsibility because it was completely my fault for being so stupid. When I first tried to merge the mesh, I was stupidly trying to preserve the lower body part of the mesh as much as possible, so I tried to do the merge where the neck meets the chin which was a nightmare. I got it merged, but the topography was so bad I had to toss out the results. Even Zbrush said "Hey, stop being stupid!" when I tried to do a little smoothing. There were ugly triangles everywhere and I felt a deep sense of shame when it was all said and done. I caused myself a couple hours worth of headaches because I was locked into thinking about the task inflexibly. Of course it would be an ugly join if I tried to do it there. After I got frustrated, I put down my mouse and was headed off to bed -defeated. As my head hit the pillow, I slipped, hit my head on the sink, and when I came to I had a revelation! Make the join further down on the neck where the geometry is simple! ARRRRGH! What was I thinking! I couldn't wait until this evening to try out my theory, so I slipped quietly into silo and gave it a test. About ten minutes later, the join was done with all quads and the subdivision tested perfectly. I'll slip it into Zbrush tonight and smooth everything out. Lesson learned.