I want to add a new Perk Entry/ Entry Point to the Master Trader Perk.

The existing Perk Entry/ Entry Point is Calculate Buy Price and adds a multiplier of 0.75 to the buy price of items. I want to add a multiplier of 1.25 to the sell price so that all bartering in the game will allow you to sell items at 125% of the normal sell price, once you have the Master Trader Perk.

There's no Calculate Sell Price Entry Point though, so how do I create one? Please help.