Another idea - but I'm not sure if I understand what You want - use "relative" timelines.
Set up an initial motion for an element - I've used the "Main Timeline" in my demo. An "On Mouse Click" event on the rectangle triggers the second timeline "GoToCenter". This timeline has a relative starting point based on where the rectangle is moving on the "Main Timeline" when it is clicked. The second timeline moves the rectangle to the center point, as defined in the the timeline "GoToCenter" (using left & top positioning).
Hype Project: RelativeTimelineDemo_JHSv1.hype.zip (19.1 KB) - Demo Here.