I'm working on a manual import from a very heavily modded phpBB2. This forum has been previously partially imported into MyBB, which is what I have already successfully imported to XenForo in a test run.
Now I'm working on fixing the issue of having two forums running, the phpBB2 one still running in read only mode due to historical value of old threads that people want to retain and check out every now and then. I can't use MyBB import again because I already have new users, threads and posts to deal with. The only things I want to import from phpBB2 are the missing users, threads and posts. Maybe private messages too if I go insane enough.
Linking existing information together to avoid duplicate data is easy enough. However with users I have one issue that is a concern: how I should deal with passwords? Does XenForo require password fields to exist for a user or can I just ignore them? Or is it (easily) possible to extend XenForo's password system to automatically upgrade passwords from phpBB2 format like MyBB does?
As a generic import question: can I just add the missing data to XenForo tables and then rebuild caches?