So, with the rumoured inclusion of Freelancer in Co-Op, those who have played Hitman Sniper: The Shadows, know that Stone and Knight are part of the ICA hit team, who have been hand picked by Diana after being granted permission from the ICA to do so.
If they are both coming into Freelancer as part of Co-Op and given that is themed to be set around post Hitman III, I can only assume that Diana has recruited Knight and Stone as part of her own murder-for-hire Freelance organisation after the destruction of the ICA, given they were both originally picked by Diana when she was part of the ICA.