Thank you Spoon, indeed changing line 4
Code:
ChildrenAlbums**Genre&+&Children&+&Album
Artist{_a_to_z_}{_no_track_list_}
Artist\Album
Album{_a_to_z_}
to
Code:
ChildrenAlbums**Genre&+&Children&+&Album
Artist{_a_to_z_}{_no_track_list_}
Artist\Album
Album
brings the desired effect of directly descending into All Albums for my custom entry in line 1.
Now, why my custom tree item depends on another line item of the standard tree is difficult to understand for me.
For me it would be more intuitive, if the custom tree item was independet and omitting {_a_to_z_} in the definition of the same line would behave like chaging line 4.