If you have a large number of Photos libraries, PowerPhotos allows you to organize your libraries into groups in the library list.
Creating groups To create a new library group, select File > New Library Group, and the new group will appear in the library list, allowing you to type a name for it. Each group has an indicator showing how many libraries are in that group, and a button containing a menu with several actions that can be taken on the group.
Arranging libraries and groups To add your existing libraries to a group, drag the library from where it is in the list and drop it into the group. You can also drag libraries directly from the Finder to add them to groups. Libraries can be reordered within a group by drag and drop, and groups themselves can be reordered as well. Once you have libraries organized into groups, you can click the triangle next to a group’s name to collapse it, making it easier to browse your groups without having to scroll through the long list of libraries.
Renaming a group To rename a group, click the “…” button and select “Rename Group” from the menu that appears.
Deleting a group You can delete a group by clicking the “…” button in the group’s row and choosing “Delete Group” from the menu that appears. When deleting a group, you’ll be given a choice for what to do with the libraries that are currently in that group. You can either remove all the group’s libraries from the library list as well, or you can move the libraries to a different group. The default “Photo Libraries” group at the top of the list is always there and cannot be deleted.