From my understanding 2 years with K2, must meet all hiring preqs for K4. Preferential interview only, bring nothing with them if hired. The only think shared with any of the companies is the name, all separate certificates and operations.
Airnet II Part 135
K9 Kalitta Charters Part 135
K2 Kalitta Charters II Part 121
K4 Kalitta Air Part 121