Using the knife project tool I have been able to scale my entire mesh to TWO resolutions, cut out (and delete) the ear from the low-resolution model, cut out the ear from the HIGH-resolution model (using the same vertex path), and graft it onto the low-resolution model:
The result is good; it is an almost perfect join. Only in a few places can I see a tiny gap.
However, it is still 2 objects, and simply joining them doesn't connect the meshes. I would like to connect the meshes so that I can smooth around the join line, and use the 'simplify' brush to transition gradually from big triangles to small triangles.
Is there any such tool?