Acts_as_tree? Heirarchy needed

Hello,

I have a problem that I thought I could solve with acts_as_tree but
I’m thinking now that acts_as_tree doesn’t quite fit the bill.

Basically I have a standard hierarchy with 1 difference:

Node 1
\ Leaf 1
\ Node 2
\ Leaf 2
\ Node 3
\ Leaf 3
\ Link back to Node 3 **** HARD BIT


                             \ Node 4
                                          \ Leaf 4
                                          \ Leaf 5

The problem is Node 3’s parent is Node 2 so linking back to Node 3 is
impossible.

i.e

node3.children.create(node5)
node5.children << node 3 – This will cause node3’s parent_id be
node5 and not node 2

Can anyone think of a way to do this??

Thanks

Iain