Appended is a patch to implement kind of a "break" on
a child entry:

-- a.org ---
a
a
* s1
b
b
* #
c
c
-----------

When doing a TAB on "* s1" only the "b" section will fold.
"* #" (a heading with name "#") is implemented as a
child that is made visible by default when when unfolding.
It is also shown by default when cycling globally.
Works at all sublevels.

-- Greetings Konrad