Hi 'Nando,
I just adopted the assignment given by the auction house; of course I am not certain about their actual provenance. Your input is all the more valuable in this context.
Anyway, my opinion, though usually as well based as possible and backed up by more than 30 years of experience, is far from claiming to be a rule. I realize there are people out there who are able to add amendments. I only wish they would do that after all! All I've been hoping for when starting this has been a lively discussion!
Still hoping for the best,
Michl