140603 integrate user database

Hello all, I'm currently using 3 different scripts and they all have different log-in/users. So i would like to pull them all into one. So user dont need to register over and over again on the same site. Here is my list of scripts: - PHP Pro Bid Auction - Download Engine v.1.4.4 - PhpBB 3.0 and 1 more small script. So if you are inerested please reply. Thank you all for your time.