Dear sergio,

I'm glad I could help.

> Oh, sorry. Thank you, Takaaki, (org-show-siblings) is exactly what
> I want! But could you say, how you've discovered it?


I have recently reading org.el to write my elisp, org-tree-slide[*1].
Your problem is very hot topic to me :-)

[*1] http://orgmode.org/worg/org-tutorials/non-beamer-presentations.html

Best regards,
Takaaki Ishikawa