Is there any way to have a spline (eg circle) control a shoulder joint (position & orientation) yet not have the spline be part of the characters skeleton?

I’m trying to export the skeleton to a game engine without exporting the controllers (baking the animations before I delete them) But the animators still want their spline controllers to animate with.

I’ve been trying to use position and rotation constraints to do the job but I haven’t figured out how I can do it yet.