Thanks guys. I will take a look at these suggestions and see if they help me do what I would like to do.
You may be thinking of a different setup, but if you are think of creating a 'Day' list with all your systems of interest, and a smaller "Night", containing only those more of interest, such as your local Law Enforcement, Fire, and EMS, then you might do this:
Create one list initially. If it's your 'day' list, put whatever you want in it. You can, of course, append many of your items from the main database, then use the Favorites Editor to clean it up if needed to remove excess talkgroups or sites (left over from the Append process). Once you've edited it, tweaking entries and text tags as needed, save any changes & return to the main Sentinel page.
If your 'night' list is composed of selected systems from your 'day' list, you can <right><click> on systems in your day list, and append them to a new list. Just right click a system to bring up the pop-up menu. Select the append function, which will bring up a list of your Favorites to append to. Select the New Favorites option, then give the new list a name. That will append the system to what will be your evening list, whatever name you care to give it. You can then append other systems from the 'day' list to your alternate night list. Of course, you also have the option of appending a totally different system (not in your day file) from the main database. Use Sentinel's Favorites Editor if needed to massage text tags or anything else.