Thank you Ben!
It´s is not quite what I am looking for. I want to have a sequence as a source in my source monitor and edit stuff from there into my “work”-sequence.
If I do so, I just get something like a compound clip. But I need to get the clips itself, like the are in the source sequence. I guessed that I might have to define how source tracks target to the “work”-sequence-tracks, but that seems to be not working.