Group sheets work slightly differently from the rest of the sheets; they offer more of a dashboard overview of linked sheets. Linking a sheet will also link all of the nest sheets below it, which can be viewed and selected from the side panel.
The main content panel to the right has two main modes, when no sheet is selected the tabs at the side will give an overview of linked NPCs, which can be filtered by type, linked entries with inventory, linked regions & locations, and quests. The and tabs allow for adding content via inline editors as per other sheets.
With a sheet selected in the sidebar the main content panel will show the content of that sheet. To go back to the main group sheet view, clicking the in the top set of tabs will deselect the sheet.
Sidebar
The Group sheet sidebar offers a tree view of the linked sheets. Journals can be dragged & dropped from the Group sheet sidebar as you would a regular journal item. The view can be filtered with the control buttons:
Expand all tree nodes
Close all tree nodes
Hide / Show Groups
Hide / Show Regions
Hide / Show Locations
Hide / Show Entries
Hide / Show NPCs
Show items in Entries
Hide / Show Tags
Tag view. This switches the tree view to put all linked tags at the top level and nest the linked sheets as nodes.
Some other context-specific buttons are:
Open the associated sheet
Unlink the associated sheet (top-level links only)