Use a Null object and parent all your layers to it. OR precomp all those layers in another composition. I'm on an iPad otherwise I'd add the help links. But look up Null and precomp or nesting. Hope it helps.
Thank you, i'll try this.
I maybe have to mention that at first, the layers are moving seperate into the screen. And after that, they have to move all at once offscreen. So they move all at once only in the 'second' part of the movie.
Thanks! This works. I've chosen the method with the Null object and placing keyframes to let the layers only 'child' with the null-object only when they have to move together.
You can still animate the layers when they are parented. Use the null object for moving them all at once. Or animate the precomposed layer (with the animation in it) out of shot.
The solution for me was as you suggested to create seperate compositions with the animation in it.
Then make a final composition with all these composition nested. Than I could easily apply the transition/whipe effect with positions and keyframes.
Makes it also a lot more easy to work with.