Feature Request:
I have controlling files for each of my podcast subscriptions and I often need to load them up with the podcasts before performing Export scripts. Not critical, but it would be nice to have an option for CTL+F to add these control files instead of me having to CTL drag them into the window.
I am not quite sure if this is something for you:
You could create a tool that calls MP3tag and adds a particular file to the current list
Create new tool in File>Options>Tools
Name: Load xxx file
Path: c:\to\Mp3tag.exe
Parameter: /add /fn:"C:\music\myfile.MP3"
(you would have to replace the names with your local ones.)
If you have a playlist with a set of files then you can load and add several files in that way
If it is a shortcut you are after, have a look at the help: https://docs.mp3tag.de/customization/options/tools
You can create up to 99 external applications here. The first ten tools can also be started by the keyboard shortcuts Ctrl + 0 to Ctrl + 9.