This is a powerful feature of TTP that allows you to share tagging efforts on a subset of your photo
library (or even all of your photos if you choose).
By updating the metadata on shared images, all people with shared access to a folder will receive the EXIF-IPTC-XMP tag information (embedded or side-car).
If multiple copies of TTP are reading from the same folder or sharing (be it a network share or
cloud-synchronized folder including Dropbox, Google Drive, and OneDrive), then changes to metadata made
by one TTP user will be picked up by any other TTP user connected to that same folder.
When changes are detected,
the steps outlined in the User Guide for handling of Modified Images are executed. On the "other TTP systems", you may need to run a "scan for changes" on the
folders from Windows Explorer to detect image changes.
Another tip is when making significant tagging changes - for a new set of photos for example - turn off the cloud sync service until you are finished. You can usually do that temporarily via the Windows Tray menu for that service. Then when you have finished the tagging task, turn the sync back on and it will catch up. The benefit is less overhead on your system while the system is making many changes, and the other users monitoring that folder will try to read those updates while it is still "a work in progress" task.
We recommend that for each folder monitored by TTP, you have one primary editor person/system to avoid confusion and conflict between metadata changes. And definitely don't have multiple people working on the same folder at the same time. The problem is that the last user saving changes will over-write any other users changes if they happen at the same time.