You are going to have to be a lot more specific about what you are trying to accomplish. From your very brief description, I really could not guess what you are asking.
A longer descrition of what you want to do and how you are going about it would be most helpful in getting you an answer to your question.
I have a friend in Los Angeles, who edits feature films and TV Movies. I posed this exact question to him, and his answer was "George, I have no idea what you are talking about".
I just sent him your answer to the question and his reply was "Oh, you want to mix two video sources and adjust the video level of one of them".
Amazing how when you do this for so long, you forget how to translate questions into editing terms. I need to work on that.