Hi Bruno, is this the issue you brought up on the Rhino forum? (Sorry, was looking for the same username.) I've looked at your animation. If I'm not misunderstanding, to return to a zero point, you would simply need to use 6 degrees for your final animation. Regardless of where your actual 0 point is located, that 0 point will be relative to the rotation animations you add. (0+5-11+6=0)
Otherwise, if I am misunderstanding, it may help if you can provide a bip. I've attached one that shows a sphere at a random location with three animations as you have described.