Sub Forms don't center over owner but Sub Form's StartUpPosition = 1 (CenterOwner)

I think maybe the problem is this:

Form1 at startup has StartUpPosition = 2 (CenterScreen).

So, Form1 shows in the center of the screen. But I need to (at times) move it here and there and when Form2 starts up it is always positioned at center of screen. I guess Form2 get's it positioning from the StartUpPosition of Form1 and uses that even though I have manually moved Form1 elsewhere. I'm not sure of this but it sure looks that way.

So, how can I ensure that Form2 will always startup centered to Form1 no matter where Form1 is positioned?