Combine Registration

I need to have an auction script's (PHPproBid) registration to be combained with the main site. Another words, when user registers into the main site, he/she will also be registered in the above mentioned auction script site which is in a sub-domain. The bidders MUST be expert in PHP+Smarty. ## Deliverables A reliable and knowledgeable coder will be awarded bonus and further projects - otherwise bad rating and no money in the bank. You choose.