Hi Klaus
glad you found it useful. I looked at your file nice job. We took the same approach (creating a new StaffGroup). This means that to continue you need to add 2 more -- another flute and another bassoon -- or else the grouping is wrong.
I changed your file however i lost the SpanBar ... not sure why.
http://mglessons.com/lilypond/try-klaus.lyI did have another approach - one without creating a new staff and using the existing flute and bassoon section. It works however I was unable to force the SpanBar and SystemStartBracket. I think ideally that would be the way to go. Any idea how to force them to appear when it's not the beginning of a system?