What I tried without success:
SetSpritePhysicsDelete(SliceSpriteID)
ClearSpriteShapes(SliceSpriteID)
SetSpriteShape(SliceSpriteID,3)
SetSpritePhysicsOn(SliceSpriteID,2)
CalculateSpritePhysicsCOM(
SecondSpriteID)
Not only that bundle, but also a combination of them.
Damn.. do u see the underlined SpriteID? that was the mistake...
I realized it after i typed that post.
It is the ID for the other half of the cutted Sprite.. so only one sprite behaved corect.
Now it works ..and the manny thanks goes toooo baxslash 
Ill put everything in a function, maybe functions if i want to make 2D portals possible.
Another problem is that I use GetImage() for the modyfied image.
Actually im using a shader to cut the image, but it does't change the image itself so I must get the image data after rendering.
Then I just get the image from the buffer and update the sprite.
But it can happen that there is another sprite in the background.
I tried render to image but the sprite was streched.
