For the moment I did nothing more, I am doing now other things.

What I found is that middle point subdivision works fine preserving the shape and a new vertices conversion table (for the morphs) can be easily generated, but middle-point subdivision only increases the mesh density and not makes it more smooth, the rendering of the subdivided mesh looks exactly the same as it was before the subdivision.To solve this problem I found a two steps solution:

Step 1- Subdivide the mesh with middle-point subdivision and create the new morphs.

Step 2- Smooth the subdivided mesh using Taubin smoothing (Laplacian smotthing with shape preservation)

 

Stupidity also evolves!