I believe you are going to have give more details before you can get a meaningful analysis/response. What were you trying to do? How did you attempt to do it? What were the expected results? What were the actual results?
Track 1 - Parent
Track 2 - Child
Track 3 and 4 - Parent
When I use compositing mode on track 1, all my lower tracks ( 3 and 4 )become affected, even Tracks 1 and 2 are empty. How to prevent this and keep tracks 3 and 4 unchanged ?