I'm not especially familiar or experienced with the "Serge" format, but would some sort of compromise or transition period be useful? Say you change the "Serge" universe to be labelled as "4U (Serge)" or "4U (formerly Serge)" or "4U (FKA Serge)", and then perhaps later on change it to simply "4U" once users have become accustomed to seeing it presented that way? Or name it something new entirely like "FKAS", short for "formerly known as Serge"? Just some ideas.