I'm not a Siberlius user either, but in editing NPOR we often need more than the basic characters (letters with acvents etc.). I use a built-in utility of Windows called "Character Map". You may have to search for it - its location has been moved in different versions of Windows, sometimes hidden under tools or similar in the full list of programmes/apps. That allows you you find all sorts of strange charachters, and either copy & paste them, or with many there's a 4 digit code that requires the ALT key to be depressed whilst it's entered in the document. Worth a try anyway.