Refresh Library without loosing watched state

Hi

My setup

Kodi 17.1 (Windows and Libreelec)
Mysql DB
Movies / TV Shows on NAS
TMM (tinymediamanager)

I manage my movies/series with tmm resulting in NFO files in each movie folder/for each episode. I added movies and series into the kodi library. Later, I sometimes change some of the NFO files. In the case of only a few changes I can refresh the movies/episodes manually.

But if a have to change a lot, I tried to set the series content to none, remove the informations from the library and set the content back to local NFO files and rescan the library. Doing it this way I loose all my watched/not watched status.

How can I reload a lot of NFO files into the library without loosing the watched status? Is there an addon/feature or something else?

This is the only pain I have with Kodi, would be nice to have a easier way to rescan NFO files.

Thanks for your help!