But wait, I think there's another designation they can use that would require a 1st and 3rd. What designation is that, anyone know?
That's known as restricted free agency. Teams have the right to match other teams' offers for their player, or they can receive compensation depending on what kind of qualifying offer they have in place. I believe it's $1.8 million for a 1st and 3rd round pick.
Edge will be an unrestricted free agent next year, meaning the Colt's will receive no compensation or the chance to match offer sheets on him. Harrison is also an unrestricted free agent at the end of the season. The big problem is that you cannot franchise/transition two players in the same season.