Actually, why filter the "played by" override at all?
If there isn't a major technical reason could you give me a checkbox in the admin panel somewhere so I can set it to always remember instead of the system deciding on its own who it'll remember and who it won't?
It'll be fairly obvious if it needs to be changed because it won't be blank. At that point then it's my fault if I mess it up, rather than the system deciding this for me.
The reason it filters that information is for those times when someone is playing on someone else's toon for class necessity. The last thing you want is for someone's legitimate DKP to remember to be assigned to someone else because they happened to play their character once when it was needed (but the player wasn't available).
This was something that happened fairly often in my guild when we raided.