Sub-sub items (grandchildren, depth > 1) odd behavior

This is best described with just an example.

If I have this as a menu tree

Parent 1
   Child 1a
   Child 1b
   Child 1c
Item 2
Parent 3
   Child 3a

and I add a child to Child 1a, (all of these are defined as Not expanded), I get (when I click on Parent 1)

Parent 1
  Child 1a
     Child 1a1
  Child 1b
  Child 1c
  Child 1d
Item 2
Parent 3
  Child 1b
  Child 1c
  Child 1d