We have to install a unique, separate, new XenForo onto our site that will be dedicated to one topic. The problem is that existing users on the existing forums wont be able to automatically participate there. They'd have to register again. We were considering a multi-site plugin, but I was wondering - it would be a lot easier if we could do this: 1) Copy all existing users into the new XF install so at least current users have access. 2) Add something to the registration screen of the native forums which could be a simple checkbox, saying "Yes, please also register me on the other Forums" 3) Checking this box acts to register them on the other install as well. Seems a lot easier than having to manage some multisite AddOn that might break, become outdated, etc. This seems a lot more basic, and just a one-time modification. Thoughts?