Work Item Supersedes value in Quick Information panel

We are using RTC 4.0.6 to track build through test environments and have created work item types to manage the workflow. Normally we link the lower level work items to a parent work item using the Add Children link. However when duplicating the parent record we have to add the existing lower level work items using Add Related as a child work item cant have two parents! :-)

However when we make the related link the Quick Information pane shows a Supersedes link to the new 'parent' work item as well as a Related link, but I cant find any help on what this 'Supersedes' value is. There is nothing in the Links tab of the work item other than the normal Related link.

Anyone know if this 'Supersedes' link can be controlled or hidden?

Thanks
Ali