how to add header multi lines
You could use the teachers' comments and legend, but it is not exactly what you suggest. I will write down your suggestion.
You can do that if you use TiTiTo. The feature is implemented there.
fixed header for all teachers and students.....
You can add any html stuff before and also after the tables.
See
TiTiTo -> Timetables -> Additional Preface
and
TiTiTo -> Timetables -> Additional Postface
thank you very very much for you brother Volker Dirr