Thanks for responding.
Here’s what I’m trying to do:
I’m making a character animation. I have the character’s lip as one layer. I have key-framed this layer using only position key frames.
This layer is parented to a head a layer. I want to set the head layer’s rotation to the key frames from the lip layer.
I don’t know if this helps, but I am used to using Motion Math in older AE versions. In Motion Math I used the “copy relative values” script to achieve what I want. I think I just need to modify the expression so that it uses relative position/rotation instead of actual position/rotation.
Does this make sense?