Force existing user rules reacceptance ?

[wellgate]

I am migrating my users and their posts to a new forum site. The rules have been updated so in order to proceed, I need to get their agreement before they continue to post once the new site is launched.

If I make them all new users, then the rules problem is solved, but then how do I relate them to the posts they made taha are imported from their previous existence ?

Is there an easy way to trigger the rules acceptance screen again for all users on their next visit, or a mod or hack that would allow me to do this ?

Thanks in advance
wellgate