Thanks for the suggestions...I currently only have one Marriott stay scheduled before the arrival, and given the rather low prevalence of Marriott's brands in Germany (at least within the limits of my company's travel policy) I doubt if I get another stay by the time I need the award. Buying makes no sense for me as well...the missing 15K points is +/- the going paid rate for the night.

So it seems I'm out of luck with this...

Greetings - Dirk