Aligning elements in animations

Thank you Math. That works nicely for the fixed paths. However, for custom paths I have two problems. First of all, I can't work out how Storyline calculates the height and width. I've used rules to find the x and y values of the start and end points of my animation in the attached screenshot. The numbers are values read off the ruler at the lines I've added. Y and height seem to make sense. However, the X value and width of the motion path don't seem to correlate with anything I've measured. It seems almost as if Storyline uses the TOTAL width of the animation path, rather than the net movement in the x axis. That makes it a very difficult method to use if e.g. your path swings left and then right like mine does.

The second issue is that custom paths require you to click the start point. Unless this is in the exact centre of the object, the object glitches when it starts of move. I usually have a stationary copy of the object on the timeline that is only visible until the moving copy starts its motion. What I end up with is a "jump" to wherever the green start point of the animation path is. For larger objects I can use the rulers and the centre handles of the object to find the centre. However, this is difficult for objects that aren't very big. Is there a way to force Storyline to start a custom animation path in the centre of the object, like it does for the built in paths?

Best wishes

Richard