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You can create threads through xenforo and convert them to articles, there's an topic option that's labeled 'promote to article'

I prefer to do it the other way around, when creating a Wordpress post you can specify which node you want a topic to be posted in.

I got lucky having a relatively new site, the problem you would have is with what you do with your current content. Best bet would be to clone your site in a dev environment and have a play with it