Is Replica part of Yuma Kuga's Black Trigger? Replica can use the powers of Yuma Kuga's Black Trigger. He also seamlessly wraps himself over Yuma's left arm when he activates the Black Trigger.

Also, the Trion soldiers Replica creates (like the Rabbit he gated in to help Osamu in episode 31 "Osamu Mikumo's Determination") can also use Kuga's trigger powers.

Is Replica part of the Black Trigger, or is he an independent component which shares the power?
No


   When Replica is largly destroyed, sent to another dimension, and does not come back for a little while,


Kuma still has his black trigger.  As a damaged trigger body is completely repaired when the user's Trion returns, the above could be reversed merely by having Kuma use his black trigger. Also Replica is frequently summoned without the use of the black trigger. While this is not all outright stated and so could easily be overruled by writers later, having the autonomous Trion soldier and the black trigger be part of the same thing is contradictory to the way triggers behave.


   Note: this does not contradict the idea that Replica could be part of Kuma's original trigger which is always active.