To add some clarity- I use the top focal point for focusing on a person's eye. It is too low in many situations and leaves too much headroom, so, I focus there and recompose. Using back button focusing and AF-C mode, what I have attempted to do previously is focus, release and then shutter button. My shutter/focus function is in the "off" setting. From my understanding when I release the back focus button- should it keep the focus that I set last? If so, then I think my subjects are moving too quickly and I am losing focus. If it does not work the way I understand it too, then I am barking up the wrong tree.