PhpAuction Modification

I have purchased Phpauction software, which works fine... but I am starting a site where someone that needs something translated from one language into another can post a reverse auction and when it is complete, the person who posted the auction will pay the lowest bidder of the project. The software is working fine as a normal auction site, but there needs to be a modification made so that the person placing the auction will pay the person who wins the auction after the job is done. The simplest way to do this I would think is to find where the variables are set for the buyer and the seller and switch them, but I have been unable to find where they are. I have not found a configuration file and I have searched through the sql tables with no success either. I am also willing to have another php site created like this one if we are unable to modify my software.