In IDimager you can relocate a catalog label to a different parent label in two ways. The most simple relocate feature is to drag the label over a new parent in the structure and then drop it there.
While this is very efficient to quickly relocate a single catalog label in the structure, it is not the most convenient way to relocate series of catalog labels to new parents because you would need to drag/drop each label separately. To replace a series of catalog labels to a new parent you can use the Catalog Manager. The Catalog Manager is the feature in IDimager that is intended to support and maintain your catalog database. The catalog structure is also part of the Catalog Manager. Start the Catalog Manager by selecting Tools -> Catalog Manager from the application's main menu. In the Catalog Manager you see each category represented as a tab sheet and within that tab there is a list of the catalog labels.
By double clicking on a label you can open its details which also shows the sub labels. In the sample above you see that I have several sub labels in Netherlands for cities that are actually part of Belgium. I'll need to replace them. Highlight each sub label in the list by clicking on them when holding the [Ctrl] button down. Once they are selected, click the button in the mini-toolbar called "replace the selected items to a new parent...". It is the icon with a tree on it. That will open a separate catalog tree where you can select the new parent for the selected catalog labels.
Then click <OK>. Notice that the selected labels are removed from the list. Now click <OK> until you return to the Catalog Manager and close the Catalog Manager. You can now see in the Catalog Explorer that the series of labels is replaced.