Sync database with exernally edited library

I'm unable to use darktable at the moment because my library is stored on an external drive which I use to edit my photos on multiple computers. I thought that since all the data is stored on the xmp file it would be easy but the databases not being synched really make this difficult. Enabling "look for updated xmps on startup" somewhat helps but it still doesn't work.

Deleting photos from one device shows skulls on other devices, and the dbmaint script doesn't seem to work. Duplicating on one device doesn't show duplicated images on other devices.
And this is just the first two things I tested.

Ideal solution would be to have an option "update database on startup", otherwise at least a manual option to "refresh" a film roll from the library.

Start by examining the dbmaint script and the existing "look for updated xmps on startup" behavior described in the issue. Reproduce the external-library cases for deletion and duplication across computers, then define whether the database should update on startup or support manual film-roll refresh. Done means changes made on one device are reflected on the others without stale entries.