How to set up Robokassa so that the commission is paid from the seller?

Question

ROBOKASSA

Tell me how to set up payment of commission from the seller, not the buyer, if the store is made on physical. face. Communication with the TP of the robokassa did not give any result. In addition to the situation described in this publication - https://habrahabr.ru/post/198284/. I can't figure out where, how and what to change to make it work more or less normally :) Site on Wordpress.