Hi Ivan, yes both can do that.
In SongKong simply select Fix Songs task and add all fields to the Never Modify or add these fields option on the Format tab
This will recognize existing MusicBrainz Ids so will not attempt to rematch them but just update the fields from MusicBrainz/Discogs. Because they are all fields are added to the Never Modify or add these fields option it will not modify any of them except adding a SongKong Id field and the Discogs Release Url field. Both fields (as well as MusicBrainz Id fields that you already have) are added automatically for smooth running of SongKong, that is why Discogs Release Url is not listed as a field in the Never Modify or add these fields option.
You may want to consider let SongKong add the Discogs Artist Url as well, this provides link from the MusicBrainz Release Artist to the corresponding Discogs Release Artist.
If you really wanted to remove the SongKong Id field it can be selected and deleted using the Metagrater task
SongKong wil also attempt to match any songs that dont have MusicBrainz ids. If you didn’t want this to happen then alternative would be to use Jaikoz and the Action:Remote Correct:Update from MusicBrainz this only does updates. You would also need to add the fields to the Preferences:MusicBrainz:Format:Never modify these fields option
In this case would need to not selected the Discogs Release Artist Url
Also need to add to the Preferences:Remote Correct:Discogs:Format:Never modify these fields option
We dont currenlty support that option. Not much demand there is also a technical issue, currently first time songs are processed by any SongKong task the metadata is written to internal database, subsequent processing of same song it checks to see if songkong is already in database and if so and the file modified date of file is not later than the date in database it reads metadata from database instead of file which is much quicker. This would be broken if last modified date could nt be relied on to actually indicate last modified date.
Maybe a workaround is there another tool or script you could use that would read the lastmodiified date, and write to a file, process songs in SongKong, and then read back the last modified date and write back to the file.