i would think like some other site that if there is a membrship bought by one themn the other should be allowed to play without any problem.. i have my daughter who is also a member, and mainly uses our computer.. sometimes the ones at school too..
I have also had the problem at one site where a frind of mine was using one computer at their house, i was using mine here.. yet we could not get into the same room together to play.. it was saying it was the same IP address.. yet no matter how many times we wrote.. it just wouldnt let us play together.. we have worked out it was to do with our isp and the way we connect !!! so if that happens here there are a lot of us who wont be able to play together.. or something?? as i have NTL broadband as do quite a few others i know too!!!