MacGuyver First let me clarify, those photo libraries have different photos, not just two copies of the same photo set? If yes, then this is how I would do that. I would create shared archive, preferrable on NAS, but external drive that you can move between PC’s would also work. So I would move my archive from one PC to that drive completley, and then connected it to second one, index it and only then would start adding new photos from second archive, using either Control+M or F6 funcitons. Both functions will merge ini files in the process.
To move archive, you can move its root folder in Explorer, then go to Library settings and change the missing path to new one.
MacGuyver One more question - If I lose one of the Tonfotos.ini files, is it not the case that the facial data has been written to the JPG files themselves, that it would be easy for Tonfotos to recreate all this info, or is that an oversimplifcation?
If you did not write faces into metadata and deleted ini files, data is still contained in Tonfotos internal database. ini file will be automatically reconstructed during next indexing. However, that is only assuming the file did not move and remains where it was.