[snip]
A has B, while B has a "parent" attribute which is
referenced back to its parent: A
Cross-referenced:
A has a child X, B also has a child, it's a reference
to the very same X
The dizzy making thing here? B is also a child of A, which
appears to be the causing this problem: php still hates references
[/snip]
I'd love to see the UML for this.