Seperare file name with just Artist and add Artist 2 to title

I want to consolidate the way my tracks are tagged and ensure that from the filename I then only have 1 artist in the artist field, any featured artists are then added to the Title field

so for example

Taylor Swift Feat Ed Sheeran - Eveyrthing Has Changed should resolve to

TITLE ARTIST
Everything has changed Feat Ed Sheeran - Taylor Swift

in the file name there is often a combination of values it can Feat, ft, &, Featuring.
Can these be combined into 1 string or has to be seperate

Thanks Bart

MP3tag is a tagging program - and not a file renamer.
So I would first of all import the data from the unstructured string in the filename to the structured information in the fields and then compose a new filename from there.

If you insist on fiddling about with just the filename, use the function Convert>Filename - Filename and e.g.
Source: %1 Feat %2 - %3
Target: %1 - %3 Feat %2

You would have to adapt that function for each different pattern to cater for

Thank you for your reply I broadly understand what you are saying

essentially seperate the tags at filename and then reconstruct the data

I tried this but think I got the syntax wrong can you show me an example please how to do this for the above example

Thank you

Use the function Convert>Filename - Tag
Format string: %artist% Feat %feat_artist% - %title%

This puts
Taylor Swift into the field ARTIST
Ed Sheeran into the user-defined field FEAT_ARTIST
Everything has changed into the field TITLE

You can now decide if you want to add the contents of FEAT_ARTIST to TITLE.
If this is the case, then I would use a dedicated separator for the featured artist like <> and also use some kind of meta character so that all the variations of Feat, ft, Featuring are avoided.
To add the contents of FEAT_ARTIST to TITLE and use a dedicated separator you can use the function
Convert>Tag-Tag for TITLE
Format string: %title% <& %feat_artist%>
Afterwards you may delete the field FEAT_ARTIST - have a look at the extended tags dialogue for that - press Alt-T.