Action to copy ARTIST to ALBUMARTIST with multiple values

I want to copy like this example:

(Existing) ARTIST=Shelly Manne & Bill Evans

to

(New) ALBUMARTIST=Shelly Manne & Bill Evans\\Shelly Manne\\Bill Evans

Can you help me format an Action that would do this?

The various "delimiters" in the existing ARTIST tag can be "&", "And", ",", "/", "-".

Thanks.

In the best possible case you can get a working action for your example
Shelly Manne & Bill Evans

But just think about this examples:
The Mamas & the Papas (groupname, not two different persons)
Duke Ellington and His Orchestra ("His Orchestra" would be a strange second album artist)
Earth, Wind & Fire (would lead to 3 names, but this is also a group name)

I don't believe that you can create a useful action for all your delimiting characters.

Good point, thanks. I wouldn't propose running this Action without manual inspection. It just makes it easier rather than retyping all the individual artist names.

Basically, you could do it this way:

Step #1: Copy the content of ARTIST unchanged into ALBUMARTIST
Step #2: Split the ALBUMARTIST by your listed delimiters into multiple album artists

Please just do this for a previously filtered and manually selected amount of tracks. Otherwise you will get unexpected results!

Step #1: Use a new action type "Format value":
Field: ALBUMARTIST
Format string: %ARTIST%
This will overwrite every content already existing in your ALBUMARTIST tag with the ARTIST content.

Step #2: Use a new action type "Split field by separator"
Field: ALBUMARTIST
Separator: Whatever you like to use, like & or , or / or -

Again: Please be very careful using such an action!

Hint:
Don't use it with multiple split characters like the word "and"! This would split the album artist
"Duke Ellington and His Orchestra" into 3 album artists:
Duke Elli
gto
His Orchestr

I think that it can be done in a single action:
Format value for ALBUMARTIST
Format string: %artist%\\$replace(%artist%, & ,\\, and ,\\)
... the list of possible separators/keywords could be extended.
I am pretty sure that some players accept multiple values for ARTIST but I doubt that they do for ALBUMARTIST - so if at all, the other way round would be ok.