You can't simply add additional frequencies all by themselves. You must add them to a system, which is where the scanner looks for conventional channels to be scanned. And, of course, that system has to be in a Favorites list.
If all five frequencies are in the same Department listing the database, then append that department. If they are in more than one department, you can highlight the one you want and append only that frequency, but Sentinel will include the system name & department where the frequency was found in the database. When appendin, use either an existing Favorites list, or have Sentinel create a new on for the first append, then use that list to contain any other appends that you want to scan together.
You can always edit one of your existing lists, then add a System & Department with just those five, or create a new Favorites with a System/Department with only those five frequencies. u2Brent has the manual edit screenshot.
Note that if you plan to use location control when you scan these frequencies, you would be better served if you appended them from the main database. That way, you are including the location details for the appended frequencies and department(s). If adding manually to a list, whether a new list, or an existing one, if you intend to use location control, then location info needs to be there. If it's not, and the location filds are blank, the scanner presumes that the location is zero degrees for both latitude & longitude, which is in the Atlantic Ocean, off the coast of Africa. Needless to say, that would be well out of any range you enter, and they would never be scanned.