@gigi3, thanks for providing that additional information. I've downloaded the Reward Point Full Suite 2.5e to take a look at the plugin's file structure.

Unfortunately, the plugin is too complicated for me to determine what's going on without spending a fair amount time (which I don't currently have) to understand its processing. I'm hoping that, by splitting this post out, you'll find some other Zen Cart store-owners who have successfully used Reward Points with Edit Orders.