So far as I can see, Blackcollar is considered a complete saga:
1) The Blackcollar
2) The Backlash Mission
3) Blackcollar: The Judas Solution
The first two were combined into one joint novel called Blackcollar
The product description for The Judas Solution
this is the long-awaited climax to the "Blackcollar" saga by Hugo-winner and New York Times numbered 1 best-seller Timothy Zahn
"Climax" sounds fairly definitive.