Copying TTreeView.Items[x] children to other TTreeView- help wanted

Aloha,

I would like help solving this problem:

I have a form with two treeviews.  When the user selects a node in
TreeView1, I'd like its child (on down) to appear, in tree form but with
each child as top level node.  A job for OnChange event.

I though I could do something like this:

  with TreeView1.Selected as TTreeNodes do
    begin
    TreeView2.Items := Item;
    end;

But that doesn't work.  And all the Add... methods take a parent, and a
string.  

So my question is along these lines: Can & how do I get a certain nodes
children into a TTreeNodes? (Which would then be easy to copy to
TreeView2.Items, say TreeView2.Items := TreeNodes1.)

Thanks,
RG