To my knowledge, no. You would have to trace the extents of all your meshes that you wished were one 1 mesh. And from there adjust your z points to where they need to be. There are other ways to work around this I'm sure, but thats what I would do in my case.
Thank you for your answers! Maxonform will do the trick, i know, but i don't have it. I think i leave them as different segments, not that big a deal. I was hoping that there was somewhere secretly hidden from my eyes that fantastic command ,,merge meshes".