Can you point me to the part of the code where this is implemented? I used the source code in my approach.
I think you may refer to other stuff, which is known as "reverse auction", which is similar with what you describe, but that's only influencing what is drawn from the reward pool, not how the actual, final reward is split.
The actual amount that someone receives, which is listed under the sbd_balance variable is eventually divided by 75/25 on the day of the payment.