Dynamic expandable scrolling menu

Flash 9 (usning AS 2.0)

I am guessing this has been done before. I am looking for some guidance (or even better an example file). This is similar and may be based off of the tutorial on this site: http://www.kirupa.com/developer/flash8/scrollpane_dynamic_mc3.htm - but instead of adding clips to the bottom - they need to be inserted in the middle as items are expanded.

I am looking to make a menu system in a fixed space that works similar to the tree component - but with the ability to attach and populate a MC from the library for each item instead of just a line of text with an icon.

This is a GIF of what I am talking about:

The main problem seems to be opening a sub-group and having all the top level items slide down the appropriate amount of space and also having the scroll bar re-adjust to the new MC height.

If anyone has done a similar project or knows of an appropriate tutorial - I would be very greatful for your help.