"But David couldn't wear H3's clothes... that was the problem..."

1.Load David
2.Export David's head, eyes and neck as objects
3.Load Hiro
4.Load David's head, eyes and neck as morph targets into Hiro
5.Smooth the neck with the morphbrush so that it matches Hiro's body
6.Adjust joint centers for the eyes to David's specs.
7.Delete Hiro's head morphs and load David's
8.Enjoy your new D3toH3 hybrid

:-)