SC to cover changing widget

How have others on the group been mapping widgets that update and don't
notify the AT of their updates...There are two scenarios I run into often.

1) there is a checkbox that when checked opens up a box below it full of
information... like an expandable tree

2) there is a notification about something, and it is inserted via
JavaScript into the page without notifying the user

 

WAI ARIA addresses these issues, but I'm wondering which SC violations
others have been using to require these fixes. 

 

1.3.1 (info & relationships) is sort of a mapping... because the information
is in appropriately related to its heading (but it's kind of a stretch)

2.1.1 (keyboard) is sort of a mapping because the information is not
available to the user on page load (but it is available after the change)

1.3.2 (meaningful sequence) is sort of a mapping because the sequence of the
code is different from the page on page load, as in the case of #1 where the
CSS is hidden until the checkbox is checked

3.3.1 (error identification) could apply if it's an error message

 

I kind of will we had a SC that said something like. 

 

SC XXXX: User is notified of changes or updates to sections of the page and
is able to focus on controls in the changed region within  3 keystrokes

 

Or something like that. Hey wcag 3....???

Can someone give me a good mapping in WCAG 2....