Hi Tom, thanks for the reply.
So, I am receiving the final comp with the foreground and background applied, and an external matte to affect only the background.
The issue is, when I bring the comp to the timeline and apply the CST, CDL and LUT from the client, everything is affected, therefore I'm working on the external matte already with some changes.
I was wondering if, with this files I have (final comp and ext. matte) I would be able to work on the background without being affected by the CST and etc.