You might want to explore the “subject bibliography” tool. My groups are defined by keywords. But I don’t believe “group” name is an option for this. Instead you would want to edit a custom field or a field you don’t usually use, to select each group and add the term or group name, that you would want them sorted by, best done by using the “move/change/copy” tool. If you do have smart groups, you probably would want to create them using this field, and then when you import new records, you would sort them to groups by editing that field, rather than drag and drop them in to the groups? I actually then regularly copy anything in the smart group to a hard wired group, so they get synced. I have them next to each other and can quickly see when the two numbers of records don’t match - and I go into the smart group, select all and drag to the “regular” group of that name.
As a suggestion to Endnote developers, it would be great if “group name” was added to the subject bibliography tool, as an field option? Since summary knows what groups a record is in, it shouldn’t be hard to implement?