Tree Manager Security issue

Hi All

We have a tree where the tree structure is pointing to account entry panel. We given access to certain users to maintian the tree but we don't want them to create any new accounts and just add whatever is the existing.

If a users go to click on add sibling or child node and they input a new value say (xyzzz which is not in account tbl) it should give thm security error upon clicking add button and not take us to account entry panel to create the new xyzzz account.

Thanks,

SAK