frazzle12 Tonfotos is not a cloud storage it does not copy your images or store it somewhere in the cloud. You can think of it as of specialized search engine for your images. It cannot access images that your computer has no access to, but it will index all images you will point it to. So, in order for several copies of application to collaborate on the same photo archive, all copies need to have access to the same archive. It can be stored on external drive, local network or virtual cloud folder, as an example. Once Tonfotos has access to it, it will write additional information on this drive, and other copies will be able to pick up this information modify and it back to other Tonfotos copies. You can read this article to get more information about synchronising information about people on the images: https://community.tonfotos.com/d/186-version-150-people-data-synchronization Apart from faces and people, you can modify image metadata (tags, locations, comments, etc.) and other copies will pick that up too.
Important addition: there is no need to buy family license if you want only two copies, for example. Two copies with different licenses will communicate just like several copies activated with the same license. This collaboration is not fixed to the license, it is fixed to your archive.