Watched status synced across devices

I have Kodi installed on my main PC for watching TV and I use OSMC on an RPi in my bedroom. They both connect to my central NAS box for my library. What is the best way to get the watched status common to both? I.e. if I watch something on OSMC, I can see when I log in to Kodi that it has been watched, and vice versa?
Many thanks

You can try MySQL library, for example:

I’ve been doing this for some time now, but taking it a bit further. I have two separate locations with routers connected via OpenVPN. I use the DB across the VPN tunnel all the time. Only issue is slow performance for MySQL over VPN.

I’m now playing with two-way replication, which is “interesting”