Batch Operation: Copy SOLOIST tag to ARTIST tag

I am kind of stuck:
I change my music server, that's why I need to to copy the contents of my (filled) "SOLOIST" tag to the (empty) "ARTIST" tag. Concerned are thousands of tracks. How can I handle this? I read the instructions on the batch operations, however, since I am new to MP3TAG, it is kind of confusing for me...
Any help would be much appreciated!

see the FAQs:

Thanks! I use \ as seperator for the values in SOLOIST, so I would use:

Action type: Format value
Format string: $meta_sep(soloist,\)


The $meta_sep() function is intended only for real multi-value fields (the same type of field but several of them). So before you use that function, check the extended tags dialogue (alt-T) if you really have several fields of the type SOLOIST or just one.

If there is just one SOLOIST, it would be
Format string: %soloist%

I have used $meta_sep(soloist,) and it's working out great. Now, I want to include the conductor. In other words, the field ARTIST is supposed to show soloist and conductor (has separate CONDUCTOR tag).
How can I do this?

Use an action of the type "Format value" for ARTIST
Format string: %artist% / %conductor%