IMO I think it is legal to update a stock scenario but give credit to the original designer first then the person who did the update in the discription. I think Rod Coles did something along these lines in updating a few scenarios from the old stocks for playability. However, like you said he made a second independent file for the DB I believe.
As for getting a hold of the original designer issue good luck!
Doug Bevard and Craig Foster were heavily into the first generation of CS. I have not seen or heard of these two gentlemen in quite a while on the net with CS; years in fact. So hence the conflict. They maybe totally out of gaming or heaven forbid not with us anymore.
As for modifying the scenario title for an update, good idea Petri!! That would make it much less confusing.
Thanks!
ItB