Corner points would be nicePlacing points in the very corners of the photos seems a practical way of sort of "anchoring" the morph, but eyeballing exactly where the corners are can be problematic. Without precise placement, your animation will suffer. In most cases, your morph will simply look slightly off -- perhaps have sections that appear not to morph at all or that display odd colors. The worst-case scenario is shown above. The software simply cannot interpret what you've done and leaves only the option of deleting the offending morph point.
Before SmartMorph became Popims Animator, there was a special function that added these corner points for you. It's a feature that should not have gone away.