Thank you very much, darkspace65, I suspected that was not possible to do it with a Skeleton Layer. I had tried to do it with a Skeleton Deformation Layer but I had the problem with the ZOrder.
This is the best way for me (at this moment), because I’ve made a lot of animations without applications (with pencil, eraser and maker 
) and I’m not accustomed to vectorize (I hate the vectorization and I love the pencil and the digital coloring, yes, definitely I need to renew my concepts ).
I’m going to try to investigate the layer order problem (I’m going to try with a Synfig older version), because the control with one general skeleton is very much better than several partial skeletons, so I see. I hope that don’t be a bug, and if it is I hope that can be solved ASAP.
Thanks again.