If you decide that the proper location for an existing page is a different subsite than the one it is currently in, then you want to "move" the page.
When you move a page, it will not let you over-write an existing page (the error message complains about a stub file already existing; if this happens either cancel or choose a different name, at least for now). If you have a page that should replace an existing page (e.g., "new_index" should replace "index"), perhaps because you have re-built it using a different template, then you must first rename the existing page (e.g., to "old_index") -- or delete it (but that is rarely the better choice), and then rename the new page in to replace it. There will unavoidably be a short period of time when anyone attempting to access the page will be told that it doesn't exist.
When you move or rename a CommonSpot page, any CommonSpot pages with links to that page will be updated to point to the page in its new location or new name, provided that those links were constructed with the Page Gallery or Page Finder dialogs in V5 and prior versions of CommonSpot, or the "Choose" dialog in V6 or later. Therefore, if you are using the rename command to replace an existing page, we suggest that you first go to the old page, before re-naming or deleting it, use the "Referring Pages" process to point all internal-to-CommonSpot links to the new page, and then do the rename process.
Login and navigate to your page that you want to move to a different subsite.
Click on the pencil tool icon at the upper-right and select Work on this Page, or Work on this Page (All Changes).
Click the "Actions" button (near the left end of the top row of the content-spanning toolbar), and select "Move Page...".
Specify the Name (which will have ".cfm" appended to become the last part of the URL -- this is the part that CommonSpot won't let collide with an existing page), the Title (which is the internal-to-CommonSpot identifier), and the Title Bar Caption (which becomes the TITLE in the HEAD section of the generated HTML).
Click on the "Save" button.
If you are replacing a previously existing page, and did not already do so, use the "Referring Pages" process to point all internal-to-CommonSpot links to the new page.