I'm using Outline mode (usually the minor mode, but it shouldn't matter) or Org mode. I have a file that looks like this:

 -*-outline-*-
 * Chapter 1
 ** Section 1.1
 *** Subsection 1.1.1
 foo
 *** Subsection 1.1.2
 bar
 ** Section 1.2
 baz
 * Chapter 2
 ** Section 2.1
 qux
 ** Section 2.2
 wib

I'm editing subsection 1.1.1 (“foo”). I want to focus on this section, so I run `C-c C-o` (`hide-other`). This is what I see:

 -*-outline-*-
 * Chapter 1
 ** Section 1.1
 *** Subsection 1.1.1
 foo...
 * Chapter 2...

In the old days of Emacs 19 (the behavior changed after 19.34 and before 20.7), I saw this:

 -*-outline-*-
 * Chapter 1
 ** Section 1.1
 *** Subsection 1.1.1
 foo
 *** Subsection 1.1.2...
 ** Section 1.2...
 * Chapter 2...

The difference is that the headers for Section 1.2 and Subsection 1.1.2 are shown, because they're a sibling of Section 1.1 which contains Subsection 1.1.1 which I'm viewing. I like that. How can I get this behavior in a modern Emacs?

What I'm mainly looking for is a way to make `hide-other` (or a separate command) show all siblings of all visible headers (if I'm in Subsection 1.1.1, I want to see the headers for Section 1.2 and Subsection 1.1.2, and so on). More generally, I'd like a command `outline-show-all-siblings-of-visible-headers`. Is there such a thing?