DEVONthink automatically updates the index of a group when you select/expand the group in the list, split, or 3-pane view. The group and its contents are updated-not the complete hierarchy of the index. Meaning, if you select your group ‘bibliography’ it will update its contents, but not the contents of ‘author’, ‘date’, etc. If you select the bibliography group, then newly added author folders should be automatically indexed into the database, but you will need to select the authors groups to update the contents of the groups. Note also that the update is one-way only-documents you add to these groups in DEVONthink will not be automatically exported out to the indexed folders in the filesystem.
If your bibliography group is at the root level of the database, there is a script ‘Update indexed Items of all database’ in the Support Assistant (Help Menu) that, when executed, will update all levels of the bibliography group. If you have indexed groups nested inside non-indexed groups, then you will want the script that korm created and posted in this thread.