I created some pages like the ones on Tools -> Define Pages Editor.

The idea is to create something like this:

MENU 1
SUB-PAGE-1a
SUB-PAGE-1b
SUB-PAGE-1c
MENU 2
SUB-PAGE-2a
SUB-PAGE-2b

and to create breadcrumbs like this:

Root -> MENU 1 ->SUB-PAGE-1b
...

Currently MENU1 is missing on breadcrumb.

How can I define that SUB-PAGE-1b is a sub-page of MENU1?