Hi, thank you for your reply,
It works on the test file I sent you, but the problem stills the same on my project file.
I sent you a new file.
For example when I move the Line 009 on the z axis, the FP gravel is moving on the Plane 001 (the plane is a editable poly).
The reset Xform utility reset doesn’t work for this case.
Thank you for your help.