How do I tween or move an object along a series of moving objects?

Imagine a rope that is made of multiple segments. They are parented to one another and move (wiggle around) using a timeline. It looks like a wiggling rope. Great!

Now, I want to move an object along that rope. Imagine a spark moving along a (wiggling) fuse wire.

Any tips on how I would go about doing this?

I've tried tweening to the different segments but not having much luck. Maybe there is a better way?

Perhaps this is a case where 'pinning' is preferable to using the scene graph? I don't know.

Thanks

The problem is my rope is a hierarchy and not only that but has a timeline controlling it. Would your idea still work?

I think the problem is that I cant attach something to an object that's moving in a timeline and then control its movement 'in addition' afterwards. It seems as soon as its controlled by a timeline or pinned to a timeline objects no move or tween commands will ever override that. DOes that sound right? Or maybe there is a way to add additional movement to an object after it has been affected by its parent/timeline.

Complicated to explain but hopefully someone understands :)

Thanks