[Actions] Checking if a string contains another string

Hi there, I'm kinda new to Mp3tag and have just started messing around with it.

I'm wanting to basically create an action that will look through the artist tag and find any mention of "feat". If this exists then what it will do will append to the end of the title tag "(feat. %artist that appears after feat.%)"

However I'm having a hard time working out how to properly search for strings within strings and using if statements inside of the format value action. As well as using regular expressions to return a section of the string.

For example. If I have a song with the %artist% field as "Artist A feat. Artist B" I want to then change the song title to be "%original title% (feat. Artist :sunglasses:". And then finally change the %artist% field to be "Artist A/Artist B". (This only happens if the artist field has feat. in it)

I'm not sure if I explained this well enough, but if someone could help me a bit that would be great.

To clarify this is within the "Format value" action.

See /t/11096/1