PlaytOnline Viewer can allow you to have four handles, which each have their own friend list. Each handle can be linked to only 8 Content IDs, so if you have 9 character slots, you need to manually link the IDs to handles so that all are linked and you have no more than 8 IDs per handle. Otherwise you will keep getting the error. Handles are accessed from the additional menu you need to bring up inside PlayOnline Viewer. I can't remember the keyboard button for it right now.