Recent answers I got from Cape Town from two different agents in the last two weeks:
- adding a Miles&More-number into an existing PNR is only possible when the ticket is not issued (Kassel fixed it the next day)
- a seat-assignation is never possible in advance (Kassel fixed it the next day)
- W Class in Europe is not upgradeable (Kassel fixed it the next day)
Closing Kassel will create such a mess that it will cost more than LH could ever save.