@ Jazz_North: I use the default V6 theme. But let me explain, because I think we're not talking about the same issue. At the bottom right of the album view all authors/performers ara shown indeed under 'Credits'. That is correct.
In the track listing however I only see the person I entered in the 'Composer' field on the General tab and those who are entered as 'Lyricist' under 'Authors and performance' in the Credits tab. If a track has two composers (as Bogumil mentioned: Lennon & McCartney) I don't want them in one field as 'Lennon & McCartney' because that would create a composer entry with that name. I want to see them as two individual composers. So I enter one in the 'Composer' field and the other on the Credits tab whit the role 'Composer'. In the track list at the top right of the album view only the one entered on the General tab is shown. When I enter a lyricist (or more) on the Credits tab, they are shown after the compsoser. I attached a screen shot from my view. For track 2 the compser Darren Bartlett is entered on the General tab. Wayne Bartlett and Roel van Kesteren are entered as 'Lyricist' on the Credits tab. In the same tab I entered the second composer of the track as 'Compser' on the Credits tab, but he doesn't show up there.

Did I answer your question 'why'? A vtrack can be composed by more than 1 composer and I want them to be shown seperately, not as a duo. Consider it the same way as a collaboration. Because 'Composer' on the General tab is not a collaboration field, I have to put the second composer somewhere. Under Credits seems the most logical place.

I hope that you as a veteran user can help me.

Greetz,
Jon