This discussion is very relevant to what has been happening at Predator Ridge Golf Resort which is near Vernon, B.C. See
www.predatorridge.com and there is a map which shows the layout of the courses.
Until recently, there were 27 holes, all designed and built under the direction of Les Furber in the 1990s. They were known as the Osprey, Red Tail and Peregrine nines. It has been a very successful resort, likely the most successful in the Okanagan Valley of B.C., which has seen a tremendous amount of development in the last 15 years.
The resort decided to add another 9 holes and hired Doug Carrick to do the design. Doug's new nine holes are completely new but with the exception of one hole on the old Peregrine 9, Doug has followed the routing of the old Peregrine 9. Each of those holes was completely rebuilt as tees and fairways were scraped out, all greens were rebuilt, new drainage, irrigation etc. The new Doug Carrick holes start after what was the 4th hole of the old Peregrine 9 and end at what was the old Peregrine 5th, however that hole has been lengthened considerably and will be the 13th and Doug has added a new hole which will be the 14th.
Considering the terrain and the real estate that was near some of the Peregrine 9, Doug did not have much if any choice but to follow the original Furber 9 holes as part of the new course.
The resort is openly advertising the new course, which will be known as the "Ridge" course, as a Doug Carrick design.
I am not being critical but it seems to me that a significant amount of the work that remains, specifically the routing for at least 8 and likely 9 of the holes, were the work of Les Furber. That course is not yet open although I have walked it a few times and it looks great but clearly different in character than the work of Les Furber. Les' greens were much more severe and undulating whereas Doug's are much more subtle. The bunker work by Doug is clearly different and there may be more distinquishing features but I will need to play it once it opens in July before I can comment further.
In conclusion, considering Ian's criteria in particular, it seems to me that the Ridge course is really in part a Les Furber design. The original Osprey and Red Tail nines by Les Furber are now known as the Predator Course.