Looking for a way to use the IF command when writing tags

Hi Everyone!
Today i have another question for you
I have been trying to make use of the Actions as they save alot of time. My Action is already giant but there is so much still to do.

For now i wanna move the ( Feat."random name" ) from the Title to the Artist Tag

So i did this Action

1.Guess Values
%title%
%title% ( Feat.%comment% )

2.Format Value
COMMENT
Feat. %comment%

3.Format Value
ARTIST
%artist% %comment%

4.Remove Fields
Comment

It is not perfect.. the "Feat. " will always end up before the artist in the Artist Tag even if there is no name going to the comment Tag with the first Action.
Therefore i would like the script to run Only IF there is %title% ( Feat."random name" ) in the title.

Two examples: One right and One wrong

Before:
Title:Bite My Tongue ( Feat.Oli Sykes ) Title:This Is The First Thing
Artist:You Me At Six Artist:You Me At Six

After:
Title:Bite My Tongue Title:This Is The First Thing
Artist:You Me At Six Feat. Oli Sykes Artist:You Me At Six Feat.

Expectation:
Title:Bite My Tongue Title:This Is The First Thing
Artist:You Me At Six Feat. Oli Sykes Artist:You Me At Six

Thank you for all the help!!
Filipe Cruz

One way to get rid of invalid entries is to apply an action or a set of them only to a filtered bunch of files. So perhaps
%title% HAS Feat.
could help.

Also see this thread that has a collection of actions to deal with the featured artist:
/t/9445/1

As the second step you can do something like this ...
Formatstring: $if(%COMMENT%,'Feat. '%COMMENT%,%COMMENT%)
... or ...
check the Tagfield COMMENT if it contains the string 'Feat.' or not, ...
have a look into the Mp3tag help manual, apply function $strstr or what you need in your special situation.
Search the Mp3tag forum, there are many examples regarding "feat", which may solve your problem.

Try to find something useful there ...
https://www.google.de/search?q=site%3Aforum...at+featuring+ft

DD.20160523.0752.CEST

Now there is no "Feat." in any artist tag but the featuring artist is now were i want it to be
Any idea?
Thank you for all the help!

Sorry, I gave just a tip how to apply an $if condition, but not a solution to your special case.
While you are testing an action and formatstrings, do it on one test file, but not against all files.
You can proove a formatstring in "Convert Tag - Tag" [Alt+5], there is a preview about the result of the given formatstring.

DD.20160523.1248.CEST