Ok, so I did manage to sort out cascading master template into a master template into a master template.....
the problem comes from referencing the template; it needs to be src="master_bla" where master_bla refers to the actually family, so it needs no extensions, *.adp or any other.
I still don't know how to reference a particular edit_this_page instance within the site. Any suggestions as always welcome.
Thanks
