DUAL MEMBERSHIP - Is it possible???

[ubeaut]

I have a pretty big site and have purchased a new licence with the intent to start a new forum with a dozen forums from my old site.

I intend to copy the old site to the new one then delete all but the forums I want to keep on the new site. I think this is probably the only way I can keep the threads and posts intact. It will also mean the membership list will come across to the new site as well and for all intents and purposes they will be the same site with different names.

My question is this:.... Is there a way to grant dual membership to both sites. ie if you join "Site A" you automatically become a member of "Site B" and viceversa and can switch between sites without the need to log into both or join both sites.

Thanks in advance.

Cheers - Neil